Parramatta Web Design: Your Complete Guide

Study of the properties of codes and their fitness

Coding theory is the study of the properties of codes and their respective fitness for specific applications. Codes are used for data compression, cryptography, error detection and correction, data transmission and data storage. Codes are studied by various scientific disciplines—such as information theory, electrical engineering, mathematics, linguistics, and computer science—for the purpose of designing efficient and reliable data transmission methods. This typically involves the removal of redundancy and the correction or detection of errors in the transmitted data.

There are four types of coding:^[1]

1. Data compression (or source coding)
2. Error control (or channel coding)
3. Cryptographic coding
4. Line coding

Data compression attempts to remove unwanted redundancy from the data from a source in order to transmit it more efficiently. For example, DEFLATE data compression makes files smaller, for purposes such as to reduce Internet traffic. Data compression and error correction may be studied in combination.

Error correction adds useful redundancy to the data from a source to make the transmission more robust to disturbances present on the transmission channel. The ordinary user may not be aware of many applications using error correction. A typical music compact disc (CD) uses the Reed–Solomon code to correct for scratches and dust. In this application the transmission channel is the CD itself. Cell phones also use coding techniques to correct for the fading and noise of high frequency radio transmission. Data modems, telephone transmissions, and the NASA Deep Space Network all employ channel coding techniques to get the bits through, for example the turbo code and LDPC codes.

History of coding theory

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This section is an excerpt from History of information theory.[edit]

The decisive event which established the discipline of information theory, and brought it to immediate worldwide attention, was the publication of Claude E. Shannon's classic paper "A Mathematical Theory of Communication" in the Bell System Technical Journal in July and October 1948.

In this revolutionary and groundbreaking paper, the work for which Shannon had substantially completed at Bell Labs by the end of 1944, Shannon for the first time introduced the qualitative and quantitative model of communication as a statistical process underlying information theory, opening with the assertion that

"The fundamental problem of communication is that of reproducing at one point, either exactly or approximately, a message selected at another point."

With it came the ideas of

• the information entropy and redundancy of a source, and its relevance through the source coding theorem;
• the mutual information, and the channel capacity of a noisy channel, including the promise of perfect loss-free communication given by the noisy-channel coding theorem;
• the practical result of the Shannon–Hartley law for the channel capacity of a Gaussian channel; and of course
• the bit - a new way of seeing the most fundamental unit of information.

Shannon’s paper focuses on the problem of how to best encode the information a sender wants to transmit. In this fundamental work he used tools in probability theory, developed by Norbert Wiener, which were in their nascent stages of being applied to communication theory at that time. Shannon developed information entropy as a measure for the uncertainty in a message while essentially inventing the field of information theory.

The binary Golay code was developed in 1949. It is an error-correcting code capable of correcting up to three errors in each 24-bit word, and detecting a fourth.

Richard Hamming won the Turing Award in 1968 for his work at Bell Labs in numerical methods, automatic coding systems, and error-detecting and error-correcting codes. He invented the concepts known as Hamming codes, Hamming windows, Hamming numbers, and Hamming distance.

In 1972, Nasir Ahmed proposed the discrete cosine transform (DCT), which he developed with T. Natarajan and K. R. Rao in 1973.^[2] The DCT is the most widely used lossy compression algorithm, the basis for multimedia formats such as JPEG, MPEG and MP3.

Source coding

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The aim of source coding is to take the source data and make it smaller.

Data can be seen as a random variable $\displaystyle X:\Omega \to \mathcal X$, where $\displaystyle x\in \mathcal X$ appears with probability $\displaystyle \mathbb P [X=x]$.

Data are encoded by strings (words) over an alphabet $\displaystyle \Sigma$.

A code is a function

$\displaystyle C:\mathcal X\to \Sigma ^*$ (or $\displaystyle \Sigma ^+$ if the empty string is not part of the alphabet).

$\displaystyle C(x)$ is the code word associated with $\displaystyle x$.

Length of the code word is written as

$\displaystyle l(C(x)).$

Expected length of a code is

$\displaystyle l(C)=\sum _x\in \mathcal Xl(C(x))\mathbb P [X=x].$

The concatenation of code words $\displaystyle C(x_1,\ldots ,x_k)=C(x_1)C(x_2)\cdots C(x_k)$.

The code word of the empty string is the empty string itself:

$\displaystyle C(\epsilon )=\epsilon$

1. $\displaystyle C:\mathcal X\to \Sigma ^*$ is non-singular if injective.
2. $\displaystyle C:\mathcal X^*\to \Sigma ^*$ is uniquely decodable if injective.
3. $\displaystyle C:\mathcal X\to \Sigma ^*$ is instantaneous if $\displaystyle C(x_1)$ is not a proper prefix of $\displaystyle C(x_2)$ (and vice versa).

Entropy of a source is the measure of information. Basically, source codes try to reduce the redundancy present in the source, and represent the source with fewer bits that carry more information.

Data compression which explicitly tries to minimize the average length of messages according to a particular assumed probability model is called entropy encoding.

Various techniques used by source coding schemes try to achieve the limit of entropy of the source. C(x) ≥ H(x), where H(x) is entropy of source (bitrate), and C(x) is the bitrate after compression. In particular, no source coding scheme can be better than the entropy of the source.

Facsimile transmission uses a simple run length code. Source coding removes all data superfluous to the need of the transmitter, decreasing the bandwidth required for transmission.

The purpose of channel coding theory is to find codes which transmit quickly, contain many valid code words and can correct or at least detect many errors. While not mutually exclusive, performance in these areas is a trade-off. So, different codes are optimal for different applications. The needed properties of this code mainly depend on the probability of errors happening during transmission. In a typical CD, the impairment is mainly dust or scratches.

CDs use cross-interleaved Reed–Solomon coding to spread the data out over the disk.^[3]

Although not a very good code, a simple repeat code can serve as an understandable example. Suppose we take a block of data bits (representing sound) and send it three times. At the receiver we will examine the three repetitions bit by bit and take a majority vote. The twist on this is that we do not merely send the bits in order. We interleave them. The block of data bits is first divided into 4 smaller blocks. Then we cycle through the block and send one bit from the first, then the second, etc. This is done three times to spread the data out over the surface of the disk. In the context of the simple repeat code, this may not appear effective. However, there are more powerful codes known which are very effective at correcting the "burst" error of a scratch or a dust spot when this interleaving technique is used.

Other codes are more appropriate for different applications. Deep space communications are limited by the thermal noise of the receiver which is more of a continuous nature than a bursty nature. Likewise, narrowband modems are limited by the noise, present in the telephone network and also modeled better as a continuous disturbance.^{[citation needed]} Cell phones are subject to rapid fading. The high frequencies used can cause rapid fading of the signal even if the receiver is moved a few inches. Again there are a class of channel codes that are designed to combat fading.^{[citation needed]}

The term algebraic coding theory denotes the sub-field of coding theory where the properties of codes are expressed in algebraic terms and then further researched.^{[citation needed]}

Algebraic coding theory is basically divided into two major types of codes:^{[citation needed]}

• Linear block codes
• Convolutional codes

It analyzes the following three properties of a code – mainly:^{[citation needed]}

• Code word length
• Total number of valid code words
• The minimum distance between two valid code words, using mainly the Hamming distance, sometimes also other distances like the Lee distance

Linear block codes have the property of linearity, i.e. the sum of any two codewords is also a code word, and they are applied to the source bits in blocks, hence the name linear block codes. There are block codes that are not linear, but it is difficult to prove that a code is a good one without this property.^[4]

Linear block codes are summarized by their symbol alphabets (e.g., binary or ternary) and parameters (n,m,d_min)^[5] where

1. n is the length of the codeword, in symbols,
2. m is the number of source symbols that will be used for encoding at once,
3. d_min is the minimum hamming distance for the code.

There are many types of linear block codes, such as

1. Cyclic codes (e.g., Hamming codes)
2. Repetition codes
3. Parity codes
4. Polynomial codes (e.g., BCH codes)
5. Reed–Solomon codes
6. Algebraic geometric codes
7. Reed–Muller codes
8. Perfect codes
9. Locally recoverable code

Block codes are tied to the sphere packing problem, which has received some attention over the years. In two dimensions, it is easy to visualize. Take a bunch of pennies flat on the table and push them together. The result is a hexagon pattern like a bee's nest. But block codes rely on more dimensions which cannot easily be visualized. The powerful (24,12) Golay code used in deep space communications uses 24 dimensions. If used as a binary code (which it usually is) the dimensions refer to the length of the codeword as defined above.

The theory of coding uses the N-dimensional sphere model. For example, how many pennies can be packed into a circle on a tabletop, or in 3 dimensions, how many marbles can be packed into a globe. Other considerations enter the choice of a code. For example, hexagon packing into the constraint of a rectangular box will leave empty space at the corners. As the dimensions get larger, the percentage of empty space grows smaller. But at certain dimensions, the packing uses all the space and these codes are the so-called "perfect" codes. The only nontrivial and useful perfect codes are the distance-3 Hamming codes with parameters satisfying (2^r – 1, 2^r – 1 – r, 3), and the [23,12,7] binary and [11,6,5] ternary Golay codes.^[4][5]

Another code property is the number of neighbors that a single codeword may have.^[6] Again, consider pennies as an example. First we pack the pennies in a rectangular grid. Each penny will have 4 near neighbors (and 4 at the corners which are farther away). In a hexagon, each penny will have 6 near neighbors. When we increase the dimensions, the number of near neighbors increases very rapidly. The result is the number of ways for noise to make the receiver choose a neighbor (hence an error) grows as well. This is a fundamental limitation of block codes, and indeed all codes. It may be harder to cause an error to a single neighbor, but the number of neighbors can be large enough so the total error probability actually suffers.^[6]

Properties of linear block codes are used in many applications. For example, the syndrome-coset uniqueness property of linear block codes is used in trellis shaping,^[7] one of the best-known shaping codes.

The idea behind a convolutional code is to make every codeword symbol be the weighted sum of the various input message symbols. This is like convolution used in LTI systems to find the output of a system, when you know the input and impulse response.

So we generally find the output of the system convolutional encoder, which is the convolution of the input bit, against the states of the convolution encoder, registers.

Fundamentally, convolutional codes do not offer more protection against noise than an equivalent block code. In many cases, they generally offer greater simplicity of implementation over a block code of equal power. The encoder is usually a simple circuit which has state memory and some feedback logic, normally XOR gates. The decoder can be implemented in software or firmware.

The Viterbi algorithm is the optimum algorithm used to decode convolutional codes. There are simplifications to reduce the computational load. They rely on searching only the most likely paths. Although not optimum, they have generally been found to give good results in low noise environments.

Convolutional codes are used in voiceband modems (V.32, V.17, V.34) and in GSM mobile phones, as well as satellite and military communication devices.

Cryptography or cryptographic coding is the practice and study of techniques for secure communication in the presence of third parties (called adversaries).^[8] More generally, it is about constructing and analyzing protocols that block adversaries;^[9] various aspects in information security such as data confidentiality, data integrity, authentication, and non-repudiation^[10] are central to modern cryptography. Modern cryptography exists at the intersection of the disciplines of mathematics, computer science, and electrical engineering. Applications of cryptography include ATM cards, computer passwords, and electronic commerce.

Cryptography prior to the modern age was effectively synonymous with encryption, the conversion of information from a readable state to apparent nonsense. The originator of an encrypted message shared the decoding technique needed to recover the original information only with intended recipients, thereby precluding unwanted persons from doing the same. Since World War I and the advent of the computer, the methods used to carry out cryptology have become increasingly complex and its application more widespread.

Modern cryptography is heavily based on mathematical theory and computer science practice; cryptographic algorithms are designed around computational hardness assumptions, making such algorithms hard to break in practice by any adversary. It is theoretically possible to break such a system, but it is infeasible to do so by any known practical means. These schemes are therefore termed computationally secure; theoretical advances, e.g., improvements in integer factorization algorithms, and faster computing technology require these solutions to be continually adapted. There exist information-theoretically secure schemes that provably cannot be broken even with unlimited computing power—an example is the one-time pad—but these schemes are more difficult to implement than the best theoretically breakable but computationally secure mechanisms.

A line code (also called digital baseband modulation or digital baseband transmission method) is a code chosen for use within a communications system for baseband transmission purposes.

Line coding is often used for digital data transport. It consists of representing the digital signal to be transported by an amplitude- and time-discrete signal that is optimally tuned for the specific properties of the physical channel (and of the receiving equipment). The waveform pattern of voltage or current used to represent the 1s and 0s of a digital data on a transmission link is called line encoding. The common types of line encoding are unipolar, polar, bipolar, and Manchester encoding.

This article contains content that may be misleading to readers. Please help improve it by clarifying such content. Relevant discussion may be found on the talk page. (August 2012)

Another concern of coding theory is designing codes that help synchronization. A code may be designed so that a phase shift can be easily detected and corrected and that multiple signals can be sent on the same channel.^{[citation needed]}

Another application of codes, used in some mobile phone systems, is code-division multiple access (CDMA). Each phone is assigned a code sequence that is approximately uncorrelated with the codes of other phones.^{[citation needed]} When transmitting, the code word is used to modulate the data bits representing the voice message. At the receiver, a demodulation process is performed to recover the data. The properties of this class of codes allow many users (with different codes) to use the same radio channel at the same time. To the receiver, the signals of other users will appear to the demodulator only as a low-level noise.^{[citation needed]}

Another general class of codes are the automatic repeat-request (ARQ) codes. In these codes the sender adds redundancy to each message for error checking, usually by adding check bits. If the check bits are not consistent with the rest of the message when it arrives, the receiver will ask the sender to retransmit the message. All but the simplest wide area network protocols use ARQ. Common protocols include SDLC (IBM), TCP (Internet), X.25 (International) and many others. There is an extensive field of research on this topic because of the problem of matching a rejected packet against a new packet. Is it a new one or is it a retransmission? Typically numbering schemes are used, as in TCP. "RFC793". RFCS. Internet Engineering Task Force (IETF). September 1981.

Group testing uses codes in a different way. Consider a large group of items in which a very few are different in a particular way (e.g., defective products or infected test subjects). The idea of group testing is to determine which items are "different" by using as few tests as possible. The origin of the problem has its roots in the Second World War when the United States Army Air Forces needed to test its soldiers for syphilis.^[11]

Information is encoded analogously in the neural networks of brains, in analog signal processing, and analog electronics. Aspects of analog coding include analog error correction,^[12] analog data compression^[13] and analog encryption.^[14]

Neural coding is a neuroscience-related field concerned with how sensory and other information is represented in the brain by networks of neurons. The main goal of studying neural coding is to characterize the relationship between the stimulus and the individual or ensemble neuronal responses and the relationship among electrical activity of the neurons in the ensemble.^[15] It is thought that neurons can encode both digital and analog information,^[16] and that neurons follow the principles of information theory and compress information,^[17] and detect and correct^[18] errors in the signals that are sent throughout the brain and wider nervous system.

• Coding gain
• Covering code
• Error correction code
• Folded Reed–Solomon code
• Group testing
• Hamming distance, Hamming weight
• Lee distance
• List of algebraic coding theory topics
• Spatial coding and MIMO in multiple antenna research
  • Spatial diversity coding is spatial coding that transmits replicas of the information signal along different spatial paths, so as to increase the reliability of the data transmission.
  • Spatial interference cancellation coding
  • Spatial multiplex coding
• Timeline of information theory, data compression, and error correcting codes

• Elwyn R. Berlekamp (2014), Algebraic Coding Theory, World Scientific Publishing (revised edition), ISBN 978-9-81463-589-9.
• MacKay, David J. C. Information Theory, Inference, and Learning Algorithms Cambridge: Cambridge University Press, 2003. ISBN 0-521-64298-1
• Vera Pless (1982), Introduction to the Theory of Error-Correcting Codes, John Wiley & Sons, Inc., ISBN 0-471-08684-3.
• Randy Yates, A Coding Theory Tutorial.

Development of web sites and apps

 

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Web development is the work involved in developing a website for the Internet (World Wide Web) or an intranet (a private network).^[1] Web development can range from developing a simple single static page of plain text to complex web applications, electronic businesses, and social network services. A more comprehensive list of tasks to which Web development commonly refers, may include Web engineering, Web design, Web content development, client liaison, client-side/server-side scripting, Web server and network security configuration, and e-commerce development.

Among Web professionals, "Web development" usually refers to the main non-design aspects of building Web sites: writing markup and coding.^[2] Web development may use content management systems (CMS) to make content changes easier and available with basic technical skills.

For larger organizations and businesses, Web development teams can consist of hundreds of people (Web developers) and follow standard methods like Agile methodologies while developing Web sites.^[1] Smaller organizations may only require a single permanent or contracting developer, or secondary assignment to related job positions such as a graphic designer or information systems technician. Web development may be a collaborative effort between departments rather than the domain of a designated department. There are three kinds of Web developer specialization: front-end developer, back-end developer, and full-stack developer.^[3] Front-end developers are responsible for behavior and visuals that run in the user browser, while back-end developers deal with the servers.^[4] Since the commercialization of the Web, the industry has boomed and has become one of the most used technologies ever.

Evolution of the World Wide Web and web development

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Origin/ Web 1.0

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Tim Berners-Lee created the World Wide Web in 1989 at CERN.^[5]

The primary goal in the development of the Web was to fulfill the automated information-sharing needs of academics affiliated with institutions and various global organizations. Consequently, HTML was developed in 1993.^[6]

Web 1.0 is described as the first paradigm wherein users could only view material and provide a small amount of information.^[7] Core protocols of web 1.0 were HTTP, HTML and URI.^[8]

Web 2.0

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Web 2.0, a term popularised by Dale Dougherty, then vice president of O'Reilly, during a 2004 conference with Media Live, marks a shift in internet usage, emphasizing interactivity.^[9][10]

Web 2.0 introduced increased user engagement and communication. It evolved from the static, read-only nature of Web 1.0 and became an integrated network for engagement and communication. It is often referred to as a user-focused, read-write online network.^[7]

In the realm of Web 2.0 environments, users now have access to a platform that encourages sharing activities such as creating music, files, images, and movies.^[11] The architecture of Web 2.0 is often considered the "backbone of the internet," using standardized XML (Extensible Markup Language) tags to authorize information flow from independent platforms and online databases.^[7]

Web 3.0

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Web 3.0, considered the third and current version of the web, was introduced in 2014. The concept envisions a complete redesign of the web. Key features include the integration of metadata, precise information delivery, and improved user experiences based on preferences, history, and interests.^{[citation needed]}

Web 3.0 aims to turn the web into a sizable, organized database, providing more functionality than traditional search engines. Users can customize navigation based on their preferences, and the core ideas involve identifying data sources, connecting them for efficiency, and creating user profiles.^[7]

This version is sometimes also known as Semantic Web.^[12]

Evolution of web development technologies

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The journey of web development technologies began with simple HTML pages in the early days of the internet. Over time, advancements led to the incorporation of CSS for styling and JavaScript for interactivity. This evolution transformed static websites into dynamic and responsive platforms, setting the stage for the complex and feature-rich web applications we have today.

• Static HTML Pages (1990s)
• Introduction of CSS (late 1990s)^[13]
• JavaScript and Dynamic HTML (1990s - early 2000s)^[14][15]
• AJAX (1998)^[16]
• Rise of Content management systems (CMS) (mid-2000s)
• Mobile web (late 2000s - 2010s)
• Single-page applications (SPAs) and front-end frameworks (2010s)
• Server-side javaScript (2010s)
• Microservices and API-driven development (2010s - present)
• Progressive web apps (PWAs) (2010s - present)
• JAMstack Architecture (2010s - present)
• WebAssembly (Wasm) (2010s - present)
• Serverless computing (2010s - present)
• AI and machine learning integration (2010s - present)

Web development in future will be driven by advances in browser technology, Web internet infrastructure, protocol standards, software engineering methods, and application trends.^[8]

Web development life cycle

[edit]

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The web development life cycle is a method that outlines the stages involved in building websites and web applications. It provides a structured approach, ensuring optimal results throughout the development process.^{[citation needed]}

A typical Web Development process can be divided into 7 steps.

Debra Howcraft and John Carroll proposed a methodology in which web development process can be divided into sequential steps. They mentioned different aspects of analysis.^[17]

Phase one involves crafting a web strategy and analyzing how a website can effectively achieve its goals. Keil et al.'s research^[18] identifies the primary reasons for software project failures as a lack of top management commitment and misunderstandings of system requirements. To mitigate these risks, Phase One establishes strategic goals and objectives, designing a system to fulfill them. The decision to establish a web presence should ideally align with the organization's corporate information strategy.

The analysis phase can be divided into 3 steps:

• Development of a web strategy
• Defining objectives
• Objective analysis

During this phase, the previously outlined objectives and available resources undergo analysis to determine their feasibility. This analysis is divided into six tasks, as follows:

• Technology analysis: Identification of all necessary technological components and tools for constructing, hosting, and supporting the site.
• Information analysis: Identification of user-required information, whether static (web page) or dynamic (pulled "live" from a database server).
• Skills analysis: Identification of the diverse skill sets necessary to complete the project.
• User analysis: Identification of all intended users of the site, a more intricate process due to the varied range of users and technologies they may use.
• Cost analysis: Estimation of the development cost for the site or an evaluation of what is achievable within a predefined budget.
• Risk analysis: Examination of any major risks associated with site development.

Following this analysis, a more refined set of objectives is documented. Objectives that cannot be presently fulfilled are recorded in a Wish List, constituting part of the Objectives Document. This documentation becomes integral to the iterative process during the subsequent cycle of the methodology.^[17]

It is crucial for web developers to be engaged in formulating a plan and determining the optimal architecture and selecting the frameworks.^{[citation needed]} Additionally, developers/consultants play a role in elucidating the total cost of ownership associated with supporting a website, which may surpass the initial development expenses.

Key aspects in this step are:

• Sitemap creation
• Wireframe creation
• Tech stack

Following the analysis phase, the development process moves on to the design phase, which is guided by the objectives document. Recognizing the incremental growth of websites and the potential lack of good design architecture, the methodology includes iteration to account for changes and additions over the life of the site. The design phase, which is divided into Information Design and Graphic Design, results in a detailed Design Document that details the structure of the website, database data structures, and CGI scripts.*

The following step, design testing, focuses on early, low-cost testing to identify inconsistencies or flaws in the design. This entails comparing the website's design to the goals and objectives outlined in the first three steps. Phases One and Two involve an iterative loop in which objectives in the Objectives Document are revisited to ensure alignment with the design. Any objectives that are removed are added to the Wish List for future consideration.^[17]

Key aspects in this step are:

• Page layouts
• Review
• Approval

No matter how visually appealing a website is, good communication with clients is critical. The primary purpose of content production is to create a communication channel through the user interface by delivering relevant information about your firm in an engaging and easily understandable manner. This includes:^{[citation needed]}

• Developing appealing calls to action
• Making creative headlines
• Content formatting for readability
• Carrying out line editing
• Text updating throughout the site development process.

The stage of content production is critical in establishing the branding and marketing of your website or web application. It serves as a platform for defining the purpose and goals of your online presence through compelling and convincing content.

During this critical stage, the website is built while keeping its fundamental goal in mind, paying close attention to all graphic components to assure the establishment of a completely working site.

The procedure begins with the development of the main page, which is followed by the production of interior pages. The site's navigational structure is being refined in particular.

During this development phase, key functionality such as the Content Management System, interactive contact forms, and shopping carts are activated.

The coding process includes creating all of the site's software and installing it on the appropriate Web servers. This can range from simple things like posting to a Web server to more complex tasks like establishing database connections.

In any web project, the testing phase is incredibly intricate and difficult. Because web apps are frequently designed for a diverse and often unknown user base running in a range of technological environments, their complexity exceeds that of traditional Information Systems (IS). To ensure maximum reach and efficacy, the website must be tested in a variety of contexts and technologies. The website moves to the delivery stage after gaining final approval from the designer. To ensure its preparation for launch, the quality assurance team performs rigorous testing for functionality, compatibility, and performance.

Additional testing is carried out, including integration, stress, scalability, load, resolution, and cross-browser compatibility. When the approval is given, the website is pushed to the server via FTP, completing the development process.

Key aspects in this step are:

• Test Lost Links
• Use code validators
• Check browser

The web development process goes beyond deployment to include a variety of post-deployment tasks.

Websites, in example, are frequently under ongoing maintenance, with new items being uploaded on a daily basis. The maintenance costs increases immensely as the site grows in size. The accuracy of content on a website is critical, demanding continuous monitoring to verify that both information and links, particularly external links, are updated. Adjustments are made in response to user feedback, and regular support and maintenance actions are carried out to maintain the website's long-term effectiveness.^[17]

Debra Howcraft and John Carroll discussed a few traditional web development methodologies in their research paper:^[17]

• Waterfall: The waterfall methodology comprises a sequence of cascading steps, addressing the development process with minimal iteration between each stage. However, a significant drawback when applying the waterfall methodology to the development of websites (as well as information systems) lies in its rigid structure, lacking iteration beyond adjacent stages. Any methodology used for the development of Web-sites must be flexible enough to cope with change.^[17]
• Structured Systems Analysis and Design Method (SSADM): Structured Systems Analysis and Design Method (SSADM) is a widely used methodology for systems analysis and design in information systems and software engineering. Although it does not cover the entire lifecycle of a development project, it places a strong emphasis on the stages of analysis and design in the hopes of minimizing later-stage, expensive errors and omissions.^[17]
• Prototyping: Prototyping is a software development approach in which a preliminary version of a system or application is built to visualize and test its key functionalities. The prototype serves as a tangible representation of the final product, allowing stakeholders, including users and developers, to interact with it and provide feedback.
• Rapid Application Development: Rapid Application Development (RAD) is a software development methodology that prioritizes speed and flexibility in the development process. It is designed to produce high-quality systems quickly, primarily through the use of iterative prototyping and the involvement of end-users. RAD aims to reduce the time it takes to develop a system and increase the adaptability to changing requirements.
• Incremental Prototyping: Incremental prototyping is a software development approach that combines the principles of prototyping and incremental development. In this methodology, the development process is divided into small increments, with each increment building upon the functionality of the previous one. At the same time, prototypes are created and refined in each increment to better meet user requirements and expectations.

Developing a fundamental knowledge of client-side and server-side dynamics is crucial.^{[citation needed]}

The goal of front-end development is to create a website's user interface and visual components that users may interact with directly. On the other hand, back-end development works with databases, server-side logic, and application functionality. Building reliable and user-friendly online applications requires a comprehensive approach, which is ensured by collaboration between front-end and back-end engineers.

Front-end development is the process of designing and implementing the user interface (UI) and user experience (UX) of a web application. It involves creating visually appealing and interactive elements that users interact with directly. The primary technologies and concepts associated with front-end development include:

The 3 core technologies for front-end development are:

• HTML (Hypertext Markup Language): HTML provides the structure and organization of content on a webpage.
• CSS (Cascading Style Sheet): Responsible for styling and layout, CSS enhances the presentation of HTML elements, making the application visually appealing.
• JavaScript: It is used to add interactions to the web pages. Advancement in JavaScript has given rise to many popular front- end frameworks like React, Angular and Vue.js etc.

User experience design focuses on creating interfaces that are intuitive, accessible, and enjoyable for users. It involves understanding user behavior, conducting usability studies, and implementing design principles to enhance the overall satisfaction of users interacting with a website or application. This involves wireframing, prototyping, and implementing design principles to enhance user interaction. Some of the popular tools used for UI Wireframing are -

• Sketch for detailed, vector-based design
• Moqups for beginners
• Figma for a free wireframe app
• UXPin for handing off design documentation to developers
• MockFlow for project organization
• Justinmind for interactive wireframes
• Uizard for AI-assisted wireframing

Another key aspect to keep in mind while designing is Web Accessibility- Web accessibility ensures that digital content is available and usable for people of all abilities. This involves adhering to standards like the Web Content Accessibility Guidelines (WCAG), implementing features like alternative text for images, and designing with considerations for diverse user needs, including those with disabilities.

It is important to ensure that web applications are accessible and visually appealing across various devices and screen sizes. Responsive design uses CSS media queries and flexible layouts to adapt to different viewing environments.

A framework is a high-level solution for the reuse of software pieces, a step forward in simple library-based reuse that allows for sharing common functions and generic logic of a domain application.^[19]

Frameworks and libraries are essential tools that expedite the development process. These tools enhance developer productivity and contribute to the maintainability of large-scale applications. Some popular front-end frameworks are:

• React: A JavaScript library for building user interfaces, maintained by Facebook. It allows developers to create reusable UI components.
• Angular: A TypeScript-based front-end framework developed and maintained by Google. It provides a comprehensive solution for building dynamic single-page applications.
• Vue.js: A progressive JavaScript framework that is approachable yet powerful, making it easy to integrate with other libraries or existing projects.

Managing the state of a web application to ensure data consistency and responsiveness. State management libraries like Redux (for React) or Vuex (for Vue.js) play a crucial role in complex applications.

Back-end development involves building the server-side logic and database components of a web application. It is responsible for processing user requests, managing data, and ensuring the overall functionality of the application. Key aspects of back-end development include:

An essential component of the architecture of a web application is a server or cloud instance. A cloud instance is a virtual server instance that can be accessed via the Internet and is created, delivered, and hosted on a public or private cloud. It functions as a physical server that may seamlessly move between various devices with ease or set up several instances on one server. It is therefore very dynamic, scalable, and economical.

Database management is crucial for storing, retrieving, and managing data in web applications. Various database systems, such as MySQL, PostgreSQL, and MongoDB, play distinct roles in organizing and structuring data. Effective database management ensures the responsiveness and efficiency of data-driven web applications. There are 3 types of databases:

• Relational databases: Structured databases that use tables to organize and relate data. Common Examples include - MySQL, PostgreSQL and many more.
• NoSQL databases: NoSQL databases are designed to handle unstructured or semi-structured data and can be more flexible than relational databases. They come in various types, such as document-oriented, key-value stores, column-family stores, and graph databases. Examples: MongoDB, Cassandra, ScyllaDB, CouchDB, Redis.
• Document stores: Document stores store data in a semi-structured format, typically using JSON or XML documents. Each document can have a different structure, providing flexibility. Examples: MongoDB, CouchDB.
• Key-value stores: Key-value stores store data as pairs of keys and values. They are simple and efficient for certain types of operations, like caching. Examples: Redis, DynamoDB.
• Column-family stores: Column-family stores organize data into columns instead of rows, making them suitable for large-scale distributed systems and analytical workloads. Examples: Apache Cassandra, HBase.
• Graph databases: Graph databases are designed to represent and query data in the form of graphs. They are effective for handling relationships and network-type data. Examples: Neo4j, Amazon Neptune.
• In-memory databases: In-memory databases store data in the system's main memory (RAM) rather than on disk. This allows for faster data access and retrieval. Examples: Redis, Memcached.
• Time-series databases: Time-series databases are optimized for handling time-stamped data, making them suitable for applications that involve tracking changes over time. Examples: InfluxDB, OpenTSDB.
• NewSQL databases: NewSQL databases aim to provide the scalability of NoSQL databases while maintaining the ACID properties (Atomicity, Consistency, Isolation, Durability) of traditional relational databases. Examples: Google Spanner, CockroachDB.
• Object-oriented databases: Object-oriented databases store data in the form of objects, which can include both data and methods. They are designed to work seamlessly with object-oriented programming languages. Examples: db4o, ObjectDB.

The choice of a database depends on various factors such as the nature of the data, scalability requirements, performance considerations, and the specific use case of the application being developed. Each type of database has its strengths and weaknesses, and selecting the right one involves considering the specific needs of the project.

Application Programming Interfaces are sets of rules and protocols that allow different software applications to communicate with each other. APIs define the methods and data formats that applications can use to request and exchange information.

• RESTful APIs and GraphQL are common approaches for defining and interacting with web services.

• Web APIs: These are APIs that are accessible over the internet using standard web protocols such as HTTP. RESTful APIs are a common type of web API.
• Library APIs: These APIs provide pre-built functions and procedures that developers can use within their code.
• Operating System APIs: These APIs allow applications to interact with the underlying operating system, accessing features like file systems, hardware, and system services.

Programming languages aimed at server execution, as opposed to client browser execution, are known as server-side languages. These programming languages are used in web development to perform operations including data processing, database interaction, and the creation of dynamic content that is delivered to the client's browser. A key element of server-side programming is server-side scripting, which allows the server to react to client requests in real time.

Some popular server-side languages are:

1. PHP: PHP is a widely used, open-source server-side scripting language. It is embedded in HTML code and is particularly well-suited for web development.
2. Python: Python is a versatile, high-level programming language used for a variety of purposes, including server-side web development. Frameworks like Django and Flask make it easy to build web applications in Python.
3. Ruby: Ruby is an object-oriented programming language, and it is commonly used for web development. Ruby on Rails is a popular web framework that simplifies the process of building web applications.
4. Java: Java is a general-purpose, object-oriented programming language. Java-based frameworks like Spring are commonly used for building enterprise-level web applications.
5. Node.js (JavaScript): While JavaScript is traditionally a client-side language, Node.js enables developers to run JavaScript on the server side. It is known for its event-driven, non-blocking I/O model, making it suitable for building scalable and high-performance applications.
6. C# (C Sharp): C# is a programming language developed by Microsoft and is commonly used in conjunction with the .NET framework for building web applications on the Microsoft stack.
7. ASP.NET: ASP.NET is a web framework developed by Microsoft, and it supports languages like C# and VB.NET. It simplifies the process of building dynamic web applications.
8. Go (Golang): Go is a statically typed language developed by Google. It is known for its simplicity and efficiency and is increasingly being used for building scalable and high-performance web applications.
9. Perl: Perl is a versatile scripting language often used for web development. It is known for its powerful text-processing capabilities.
10. Swift: Developed by Apple, Swift is used for server-side development in addition to iOS and macOS app development.
11. Lua: Lua is used for some embedded web servers, e.g. the configuration pages on a router, including OpenWRT.

Implementing security measures to protect against common vulnerabilities, including SQL injection, cross-site scripting (XSS), and cross-site request forgery (CSRF). Authentication and authorization mechanisms are crucial for securing data and user access.

Thorough testing and debugging processes are essential for identifying and resolving issues in a web application. Testing may include unit testing, integration testing, and user acceptance testing. Debugging involves pinpointing and fixing errors in the code, ensuring the reliability and stability of the application.

• Unit Testing: Testing individual components or functions to verify that they work as expected.
• Integration Testing: Testing the interactions between different components or modules to ensure they function correctly together.
• Continuous Integration and Deployment (CI/CD): CI/CD pipelines automate testing, deployment, and delivery processes, allowing for faster and more reliable releases.

Full-stack development refers to the practice of designing, building, and maintaining the entire software stack of a web application. This includes both the frontend (client-side) and backend (server-side) components, as well as the database and any other necessary infrastructure. A full-stack developer is someone who has expertise in working with both the frontend and backend technologies, allowing them to handle all aspects of web application development.

• MEAN (MongoDB, Express.js, Angular, Node.js) and MERN (MongoDB, Express.js, React, Node.js) are popular full-stack development stacks that streamline the development process by providing a cohesive set of technologies.

Efficient web development relies on a set of tools and environments that streamline the coding and collaboration processes:

1. Integrated development environments (IDEs): Tools like Visual Studio Code, Atom, and Sublime Text provide features such as code highlighting, autocompletion, and version control integration, enhancing the development experience.
2. Version control: Git is a widely used version control system that allows developers to track changes, collaborate seamlessly, and roll back to previous versions if needed.
3. Collaboration tools: Communication platforms like Slack, project management tools such as Jira, and collaboration platforms like GitHub facilitate effective teamwork and project management.

Security is paramount in web development to protect against cyber threats and ensure the confidentiality and integrity of user data. Best practices include encryption, secure coding practices, regular security audits, and staying informed about the latest security vulnerabilities and patches.

• Common threats: Developers must be aware of common security threats, including SQL injection, cross-site scripting (XSS), and cross-site request forgery (CSRF).
• Secure coding practices: Adhering to secure coding practices involves input validation, proper data sanitization, and ensuring that sensitive information is stored and transmitted securely.
• Authentication and authorization: Implementing robust authentication mechanisms, such as OAuth or JSON Web Tokens (JWT), ensures that only authorized users can access specific resources within the application.

Agile is a set of principles and values for software development that prioritize flexibility, collaboration, and customer satisfaction. The four key values are:

• Individuals and interactions over processes and tools.
• Working software over comprehensive documentation.
• Customer collaboration over contract negotiation.
• Responding to change over following a plan.

1. Iterative and incremental development: Building and refining a web application through small, repeatable cycles, enhancing features incrementally with each iteration.
2. Scrum and kanban: Employing agile frameworks like Scrum for structured sprints or Kanban for continuous flow to manage tasks and enhance team efficiency.
3. Cross-functional teams: Forming collaborative teams with diverse skill sets, ensuring all necessary expertise is present for comprehensive web development.
4. Customer collaboration: Engaging customers throughout the development process to gather feedback, validate requirements, and ensure the delivered product aligns with expectations.
5. Adaptability to change: Embracing changes in requirements or priorities even late in the development process to enhance the product's responsiveness to evolving needs.
6. User stories and backlog: Capturing functional requirements through user stories and maintaining a backlog of prioritized tasks to guide development efforts.
7. Continuous integration and continuous delivery (CI/CD): Implementing automated processes to continuously integrate code changes and deliver updated versions, ensuring a streamlined and efficient development pipeline.

• Outline of web design and web development
• Web design
• Web development tools
• Web application development
• Web developer