Where the Internet Came From: Why You’re Able to Read This Article

30 years ago, Sir Tim Berners-Lee’s post on August 6, 1991, in the alt.hypertext newsgroup is considered one of the earliest public announcements of the World Wide Web project. This post introduced the concept to a wider audience beyond CERN.

Here is a reproduction of that message:

Subject: WorldWideWeb: Summary
From: timbl@info.cern.ch (Tim Berners-Lee)
Date: Mon, 6 Aug 1991 15:00:41 GMT
Organization: CERN European Laboratory for Particle Physics

The WorldWideWeb (WWW) project aims to allow links to be made to any information anywhere. 

The WWW was started to allow high energy physicists to share data, news, and documentation. We are very interested in spreading the web to other areas, and having gateway servers for other data. Collaborators welcome!

Details of the WWW may be found in news:alt.hypertext on www.cern.ch, by telnet info.cern.ch, or by writing to me.

Tim Berners-Lee
WWW project
CERN
1211 Geneva 23, Switzerland
tel: +4122 767 3755
fax: +4122 767 7155

The alt.hypertext newsgroup was a part of the Usenet system, a distributed discussion system that predates the modern internet as we know it. Usenet was established in 1980 and quickly became a popular platform for discussion, file sharing, and information exchange.

alt.hypertext specifically was a newsgroup dedicated to the discussion of hypertext systems, technologies, and related topics. Given the nature of its focus, it was an appropriate place for Sir Tim Berners-Lee to introduce the World Wide Web project in 1991.

Before beginning to examine this journey more in-depth, here is brief a timeline of HTML, tracing its evolution from the concept of hypertext to its modern implementation.

Hypertext and Early Concepts: The seeds of HTML can be found in the idea of “hypertext”, a term coined in the 1960s by Ted Nelson. Hypertext refers to text displayed on a computer or other electronic device with references (hyperlinks) to other text, allowing readers to navigate from one set of text to another. This non-linear approach to information became the foundation for the eventual development of the World Wide Web.

Influence of SGML: The next key milestone was the development of the Standard Generalized Markup Language (SGML) in the 1970s. SGML wasn’t a markup language per se but a meta-language, a standard for defining types of markup languages. Conceived by Charles Goldfarb, Edward Mosher, and Raymond Lorie, SGML provided a systematic way to describe document structure, making it possible to define a myriad of document types and their respective markup specifications.

CERN and the World Wide Web: Fast forward to the late 1980s. At CERN, the European physics research center, there was a growing need to share and manage vast amounts of information among scientists. Sir Tim Berners-Lee, working at CERN, recognized this need and envisaged a system that would utilize hypertext to link and access information across different computers. This vision was the birth of the World Wide Web.

Established in 1954, CERN is one of the world’s largest and most respected centers for scientific research. Currently, it is best known for its Large Hadron Collider.

Sir Tim Berners-Lee and HTML 1.0: In 1990, Berners-Lee developed the foundational tools of the web: the first web browser, web server, and the HyperText Markup Language (HTML). HTML was an application of SGML, tailored for the web. The initial version of HTML had a basic set of tags that allowed users to create and format documents, including the ability to link to other documents, forming a web of interconnected information.

HTML Standards and Versions: As the web gained traction, the need for standardization became evident. In 1994, the World Wide Web Consortium (W3C) was founded to provide a standardized approach to web technology, including HTML. The W3C began releasing official versions of HTML, with each iteration introducing new features, tags, and attributes. Over the years, versions like HTML 3.2 and HTML 4.01 were introduced, reflecting the rapidly evolving needs of web developers and users.

Modern Day: DOM vs. SGML: By the time HTML5 was being developed, the web had significantly evolved. Sites were no longer static pages but dynamic applications. HTML5 shifted the focus from a purely SGML-based definition to one based on the Document Object Model (DOM). The DOM is a programming interface that represents the structure of a document as a tree of objects, allowing for real-time manipulation and interaction. While the syntactic roots of HTML in SGML remain evident, the behavioral aspects of web documents—how browsers should render and interact with content—are now defined in terms of the DOM. This transition reflects the modern web’s dynamic, interactive nature and the need for a robust, standardized framework to support it.

Hypertext: The Fundamental Concept

Definition: Hypertext refers to text that is not constrained to be linear. It’s a system where bits of text (or other data like images, videos, etc.) are interconnected in such a way that they can lead the reader in multiple directions, based on the choices they make. This is often achieved using hyperlinks.

Ted Nelson: The Visionary Behind the Idea

Early Years: Ted Nelson introduced the terms “hypertext” and “hypermedia” in the 1960s, long before the creation of the World Wide Web. While the rudimentary idea of non-linear writing and interconnected ideas can be traced back to ancient times and various sources, it was Nelson who articulated and promoted a comprehensive vision for them in the digital age.

Project Xanadu: Nelson’s vision was crystallized in Project Xanadu, which he began in 1960. Xanadu aimed to create a computer network with a simple user interface that allowed people to create, access, and connect documents and data in novel ways. The primary goals of Xanadu included:

Bidirectional linking: Unlike the one-way links we commonly use on the modern web, Nelson’s vision incorporated links that were two-way. This means if Document A linked to Document B, you could also see from Document B that it was linked from Document A.
Preserving all versions of documents: Xanadu aimed to keep every version of a document, enabling users to trace its evolution.
Micropayments for content creators: Nelson envisaged a system where content creators would be compensated for their work through a system of micropayments each time their content was accessed.

Challenges: Despite its groundbreaking concepts, Project Xanadu faced multiple hurdles. There were technical challenges, shifts in the project’s direction, funding issues, and more. As a result, Xanadu was never fully realized in the way Nelson had originally envisioned.

Influence on the Digital Landscape

Even though Xanadu wasn’t brought to fruition as intended, Ted Nelson’s ideas were highly influential.

Conceptual Influence: The concept of hypertext was crucial to many subsequent developments, including the creation of the World Wide Web. While Berners-Lee’s implementation of hypertext was different from Nelson’s original vision (for instance, the WWW uses one-way linking), the foundational idea of interconnecting information in a non-linear manner is the same.
Continued Advocacy: Nelson has remained a prominent figure in the tech world, advocating for his vision of what the digital landscape should look like, critiquing current implementations, and suggesting alternatives. His ideas have continued to inspire discussions around the evolution of digital information systems.

In essence, Ted Nelson’s vision of hypertext laid the conceptual groundwork for many of the digital innovations that followed, challenging conventional notions of how information should be organized, accessed, and connected in a digital environment.

The 1960s and 1970s were foundational years for the development of the Internet and the concepts that would eventually lead to the World Wide Web. Let’s explore this era in more detail:

1960s:

1. ARPANET:

The foundational concept of the Internet originated from the development of ARPANET (Advanced Research Projects Agency Network), commissioned by the U.S. Department of Defense’s Advanced Research Projects Agency (ARPA).
Its creation in 1969 marked the birth of the first practical schematics for a global network of computers. The initial idea was to share resources and ensure communication continuity in the event of a nuclear attack.

2. Packet Switching:

A groundbreaking concept called packet switching emerged, which was crucial for effective and efficient data transmission over a network. In packet switching, data is broken down into smaller packets, sent individually over the network, and then reassembled at their destination.
Independently, Paul Baran, Leonard Kleinrock, and Donald Davies contributed to this idea.

3. Interface Message Processor (IMP):

The first node of ARPANET was installed at UCLA, where Leonard Kleinrock’s team sent the first message to Stanford Research Institute via an Interface Message Processor (IMP). This event marked the first instance of computer-to-computer communication.

1970s:

1. Expansion of ARPANET:

The 1970s saw the rapid expansion of ARPANET, connecting numerous universities and research institutions across the United States. This growth laid the groundwork for the Internet as we know it today.

2. Transmission Control Protocol (TCP):

In 1973, Vint Cerf and Bob Kahn introduced the Transmission Control Protocol (TCP), which would become the major transport protocol of the Internet. It ensured reliable, ordered, and error-checked delivery of data between computers.

3. Email:

Email, a pivotal application of the Internet, was introduced by Ray Tomlinson in the early 1970s. The “@” symbol was used to differentiate between the user’s name and the machine they were using, a convention that remains in place today.

4. Ethernet:

Bob Metcalfe, in 1973, introduced Ethernet, a technology that allowed computers in close proximity to share resources, further advancing networking capabilities.

5. Transition to TCP/IP:

By the late 1970s, TCP was split into two parts: TCP for transmission control and IP (Internet Protocol) for routing and addressing. Together, TCP/IP became the standard protocol suite for ARPANET in 1983 and remains the primary protocol for the modern Internet.

6. Usenet and Bulletin Board Systems (BBS):

These were early precursors to modern online forums and social media. Both allowed users to post messages, share software, and discuss topics of interest.

Throughout the 1960s and 1970s, while the foundational technologies of the Internet were being developed, its usage was predominantly among specialized communities in research, academia, and defense. The broader public didn’t have a standardized, user-friendly way to access the vast reservoir of shared data, leading to the eventual creation of the World Wide Web in the late 1980s.

The development and inception of ARPANET is a key chapter in the history of modern computing and the Internet. Let’s delve deeper into its story.

ARPANET: A Deeper Look

1. Background & Motivation:

Cold War Context: During the Cold War, there was a heightened sense of urgency in the U.S. to develop advanced technological and communication capabilities. This was particularly in the face of potential nuclear threats from the Soviet Union. There was a fear that centralized communication systems could be taken out in a single attack, crippling communication capabilities.
Distributed Networking: This fear sparked interest in creating a decentralized network of computers. Unlike a centralized system where everything connects to a single hub, in a decentralized network, data can be routed through multiple paths, ensuring communication even if some parts of the network are compromised.

2. The Birth of ARPANET:

Advanced Research Projects Agency (ARPA): Founded in 1958 in response to the Soviet launch of Sputnik, ARPA’s goal was to establish the U.S. as a leader in science and technology applicable to the military. The idea of ARPANET was one such project that fell under ARPA’s umbrella.
J.C.R. Licklider: Often considered the “father of the Internet”, Licklider introduced the idea of an “Intergalactic Network” of computers. While at ARPA, he shared this vision where everyone could be interconnected and access programs and data from any site.

3. The Initial Goal:

Resource Sharing: One of ARPANET’s primary goals was to allow researchers in different locations to utilize powerful mainframe computers from anywhere. Before ARPANET, if institutions wanted to use a particular mainframe computer, they often had to reserve time on it in advance and sometimes even physically travel to the location.
Communication Continuity: As mentioned, another motivation was to design a network that could withstand potential nuclear attacks, ensuring that communication remains intact even if several nodes or connections were destroyed.

4. First Connection and Growth:

First Nodes: The first ARPANET link was established on October 29, 1969, between the University of California, Los Angeles (UCLA) and the Stanford Research Institute (SRI). By the end of 1969, four nodes were part of ARPANET: UCLA, SRI, the University of California, Santa Barbara, and the University of Utah.
Rapid Expansion: ARPANET grew rapidly throughout the 1970s, connecting numerous universities, research institutions, and military bases across the United States.

5. Legacy:

Foundation of Modern Internet: While ARPANET was decommissioned in 1990, its foundational principles served as the backbone for the development of the modern Internet. The project introduced several innovations, including packet switching and the TCP/IP protocol suite, which remain integral to today’s Internet architecture.

In conclusion, ARPANET wasn’t just a network; it was a revolutionary idea that paved the way for the interconnected digital world we inhabit today. The project was a blend of military strategy, advanced research, and the vision of a connected future.

The expansion of ARPANET during the 1970s was a pivotal period that laid the groundwork for the Internet’s growth. Here’s a detailed look at ARPANET’s expansion during this decade:

ARPANET’s Rapid Expansion in the 1970s:

1. Early Growth:

By the end of 1971, just two years after its inception, ARPANET had grown from the initial 4 nodes to 23 nodes. These nodes were predominantly at universities and research institutions across the U.S.

2. New Protocols and Technologies:

NCP (Network Control Protocol): In 1970, the Network Control Protocol was introduced as the first standard networking protocol on ARPANET, allowing different computers to communicate with each other.
Email: In 1971, Ray Tomlinson introduced the use of the “@” symbol in email addresses, laying the foundation for the email system we know today. By 1973, email made up 75% of ARPANET’s traffic.

3. Expansion Beyond Academia:

While the initial growth of ARPANET was primarily among research institutions and universities, by the mid-1970s, military bases, government institutions, and other entities started joining the network.

4. Cross-country Links:

In 1973, ARPANET went transcontinental with the addition of the University College of London in England and the Royal Radar Establishment in Norway. This was a major step in turning ARPANET into a truly international network.

5. Introduction of TCP/IP:

In 1973, Vint Cerf and Bob Kahn began development on the Transmission Control Protocol (TCP), which would later integrate with the Internet Protocol (IP) to become TCP/IP, the standard networking protocol suite.
By 1983, TCP/IP became the standard for ARPANET, replacing NCP. This shift was a significant milestone, laying the groundwork for the modern Internet.

6. Public Demonstrations:

In 1972, the first public demonstration of ARPANET took place at the International Computer Communication Conference (ICCC). It showcased ARPANET’s potential, increasing interest and fostering growth.

7. Proliferation of Specialized Networks:

As ARPANET expanded, other networks started to emerge. One notable example was SATNET, a satellite-based network, and another was MILNET, a military offshoot of ARPANET.
Efforts began to interconnect these separate networks, leading to the concept of “internetworking” — a network of networks. This was the foundation of the modern “Internet.”

8. Decommissioning and Transition:

By the late 1980s, ARPANET’s role had diminished with newer networks coming into prominence. It was officially decommissioned in 1990. However, its legacy lived on in the broader Internet that had blossomed from its pioneering foundations.

Throughout the 1970s, ARPANET’s expansion was not just about adding more nodes but also about advancing technology, protocols, and ideas. It acted as a living laboratory for innovations that would shape digital communication for decades to come.

By the late 1980s, while ARPANET had been revolutionary in laying the groundwork for the Internet, several other networks had emerged, both in the United States and internationally. Many of these networks served specific purposes or communities and reflected the rapidly expanding and diversifying landscape of digital communication. Here’s a closer look at some of these networks:

1. NSFNET:

The National Science Foundation Network was a significant successor to ARPANET in the U.S. Created in the mid-1980s, NSFNET aimed to connect researchers and educators by providing a national high-speed backbone. Initially, it linked supercomputing centers, but later it expanded, connecting various universities.
By the early 1990s, NSFNET had become the primary backbone for U.S. Internet infrastructure, surpassing ARPANET in terms of importance and reach.

2. MILNET:

An offshoot of ARPANET, MILNET was developed for military communications. While ARPANET continued to serve research communities, MILNET catered to the U.S. Department of Defense. Over time, as ARPANET became more civilian and research-oriented, MILNET took over the defense-related traffic.

3. BITNET:

Standing for “Because It’s Time NETwork,” BITNET started in 1981, connecting academic institutions. Unlike ARPANET, which used packet-switching, BITNET was a point-to-point “store and forward” network, primarily used for email and file transfers.

4. UUCP and Usenet:

UUCP (Unix-to-Unix Copy Protocol) was not a network in the traditional sense but rather a system that allowed Unix computers to transfer files and messages. It became popular for email and news-sharing.
Usenet, often linked with UUCP, was a global discussion system. It allowed users from around the world to discuss various topics in newsgroups. While not strictly a network itself, it relied on UUCP and later on TCP/IP for distribution, making it an integral part of the early Internet community.

5. International Developments:

Outside the U.S., several networks were emerging. Examples include JANET in the UK (Joint Academic Network), which connected universities and research institutions.
EARN (European Academic and Research Network) in Europe, NORDUnet in the Nordic countries, and others began to connect academic institutions on a global scale.

6. Commercial Networks:

With the growth of personal computing and the potential of digital communication, several commercial networks sprouted up during the 1980s. These included CompuServe, AOL (America Online), and Prodigy. These services often provided their own isolated content but would eventually become gateways to the broader Internet.

By the late 1980s and early 1990s, the digital landscape was changing rapidly. The rise of personal computing, the proliferation of commercial online services, and the diversification of academic and research networks meant that ARPANET’s pioneering role had been overtaken by newer, more advanced, or specialized networks. Thus, in 1990, ARPANET was formally decommissioned, marking the end of an era but also highlighting the beginning of the modern, expansive Internet age.

HTML’s design is derived from the Standard Generalized Markup Language (SGML), a system for organizing and tagging elements of a document. Let’s dive deeper into this relationship:

SGML: An Overview SGML is a standard for how to specify a document markup language or tag set. It’s a meta-language, meaning that it’s a language for describing other languages. In particular, SGML is used to define markup languages for representing the structure of a document. HTML, which stands for HyperText Markup Language, is a markup language defined in terms of SGML.

Origins and Creation SGML has its roots in the work of Charles Goldfarb, Edward Mosher, and Raymond Lorie, who were employees of IBM. In the late 1960s, they developed a system called GML (Generalized Markup Language). GML was created to solve the problem of handling large-scale projects, like the production of technical documentation for IBM’s hardware and software products. The main idea was to separate the content of a document from its presentation, ensuring that the content could be managed and published in a consistent way across different platforms and formats.

Goldfarb, the principal architect, later played a key role in transforming GML into SGML. He worked closely with the American National Standards Institute (ANSI) and the International Organization for Standardization (ISO) to develop SGML as an international standard. In 1986, SGML was officially adopted as ISO 8879.

Key Concepts

Separation of Content and Presentation: SGML allows the structure and content of a document to be defined separately from its appearance. This ensures content consistency and portability across different systems and presentation formats.
Descriptive Markup: Instead of defining how content should look (procedural markup), SGML describes what the content is. For example, instead of saying “make this text bold,” it says “this text is a heading.”
Document Type Definition (DTD): One of the foundational concepts in SGML is the DTD, which defines the rules and the structure for a class of documents. It specifies which elements can appear in a document, in what order, and how they relate to each other.

Usage and Legacy Originally, SGML was intended for large organizations needing to manage and publish large volumes of complex documents. This included industries like aerospace, defense, and publishing. Over time, SGML’s influence grew, particularly with the advent of the World Wide Web.

HTML, which forms the foundation of the web, was originally defined as an application of SGML. Later on, XML (Extensible Markup Language) was also developed as a simplified subset of SGML, and it has since become a standard for a wide range of applications, from web services to configuration files and beyond.

While SGML itself is not commonly used for web development today, its legacy can be seen in the structure and philosophy of both HTML and XML.

SGML (Standard Generalized Markup Language):

Definition: SGML is a meta-markup language, which means it’s a language for defining markup languages. In essence, SGML provides a way to describe how documents in a particular type of markup language should be structured.
Origins: SGML’s development started in the 1960s and 1970s, primarily through the work of Charles Goldfarb, Edward Mosher, and Raymond Lorie, who were working at IBM at the time. They were trying to create a system to represent legal and technical documents in a standard format.
Purpose: SGML was designed to be platform-independent and was primarily used for large-scale documentation projects where consistency and longevity of the documents were crucial. It wasn’t specifically designed for web content, but its principles proved adaptable for that purpose.

HTML and SGML:

Derivation: HTML was described as an application of SGML. This means that HTML used the rules and syntax of SGML but was tailored for web documents. When Tim Berners-Lee designed HTML, he used SGML’s principles to define the tags and their hierarchical relationships.
DOCTYPE Declaration: In many HTML documents, especially older ones, you might see a <!DOCTYPE> declaration at the top. This is a direct inheritance from SGML. The DOCTYPE tells the browser which version of HTML (or other SGML application) the document is using, so it knows how to properly render the document.
Limitations and Simplifications: HTML is a much simpler subset of SGML. While SGML is very flexible and can be used to define a vast array of document types, HTML was specifically designed for web content. Therefore, many of SGML’s more complex features were omitted in HTML to make it easier to use and implement.

In conclusion, while the original HTML was heavily influenced by SGML, the web’s needs and the evolution of technology have since led HTML down its own distinct path. Nonetheless, understanding this lineage gives insight into the foundational principles of web document structuring.

HTML (HyperText Markup Language) is the standard markup language used to create and design web pages. It’s a cornerstone technology of the World Wide Web. Here’s a brief history of its development:

Origins and Early Days:

1989: The Birth of the World Wide Web

Context: By the late 1980s, the Internet had been around for a couple of decades, connecting various computer networks worldwide. However, its usage was largely confined to government agencies, academia, and research institutions. There was no standardized way to access and share documents or data across these networks.

Tim Berners-Lee at CERN: Sir Tim Berners-Lee, working at CERN (the European Organization for Nuclear Research), recognized the need for a unified information system that would be easily accessible and comprehensible to users, irrespective of the platform they were using. CERN, with its vast and global community of physicists, was a microcosm of the larger world’s fragmented information networks. The problem of efficient information exchange among CERN’s community reflected the challenges faced by the broader scientific and academic world.

Proposal: In March 1989, Berners-Lee submitted a proposal for a project that aimed to utilize hypertext to meet the increasing demand for information-sharing among physicists. Hypertext is text displayed on a computer or other electronic devices with references (hyperlinks) to other text that users can immediately access. His proposal was initially met with a lukewarm response but eventually gained traction.

1990: From Concept to Reality

First Web Browser & Server: By the end of 1990, with the help of Belgian computer scientist Robert Cailliau, Berners-Lee had developed the first-ever web browser, which was also an editor, aptly named “WorldWideWeb” (later renamed Nexus). Alongside this, he also wrote the first web server software, “CERN httpd” (HTTP Daemon), which allowed computers to host websites and serve them to users.

Introduction of Hypertext: The concept of “hypertext” wasn’t entirely new, with its origins tracing back to visionaries like Ted Nelson in the 1960s. However, it was Berners-Lee’s implementation in the context of the WWW that made it revolutionary. Hypertext allowed users to navigate seamlessly from one document to another, connecting disparate pieces of information via clickable links. This was a paradigm shift from the linear reading experience people were accustomed to.

HTML – The Foundation: For the WWW to function as envisioned, there was a need for a standardized way to create and format these hypertext documents. This led to the creation of HyperText Markup Language (HTML). HTML would be used to ‘mark up’ or annotate the text, indicating which parts should be links, which parts should be headers, paragraphs, etc. The goal was to ensure that any document, regardless of its origin or the machine it was created on, could be rendered and displayed consistently across the web.

1991: Spreading the Word

The First Public Release: In 1991, Berners-Lee publicly introduced HTML to the world, along with the first web browser and server software. The initial version of HTML was quite rudimentary, with a limited set of tags that primarily focused on basic formatting and linking capabilities.

Significance: The introduction of HTML was a groundbreaking moment. It democratized the creation and sharing of information on the web. Unlike previous information-sharing systems, which were often proprietary or platform-specific, HTML was open and accessible. Anyone could create a webpage, link it to others, and share knowledge on an unprecedented scale.

In essence, the early years from 1989 to 1991 marked the transition of the World Wide Web from a conceptual idea to a tangible, revolutionary platform. The creation of the first web browser, server, and HTML were seminal steps in shaping the digital age.

Evolving Standards and Versions:

1995: HTML 2.0 became the standard. The Internet was starting to grow in popularity, and so was the need for a more structured version of HTML.
1997: The World Wide Web Consortium (W3C) released HTML 3.2, which included new features like tables and applets.
1999: HTML 4.0 (later revised to 4.01) was introduced, bringing more formatting options, improved structure, and support for stylesheets. This is also when the separation between structure (HTML) and style (CSS) became clearer.

Key Collaborators with Tim Berners-Lee:

Robert Cailliau: A Belgian computer scientist, Cailliau was one of the first people to collaborate with Berners-Lee on the WWW project at CERN. Together, they wrote the first proposal for the World Wide Web in 1990 and presented it to the European Organization for Nuclear Research (CERN). Cailliau later worked on the development of browsers for the Macintosh platform. He played a pivotal role in garnering support for the project within CERN.
Nicola Pellow: She was a math undergraduate from the University of Leicester when she joined the WWW team at CERN. She wrote the “Line Mode Browser,” which was the second web browser ever created (after Berners-Lee’s own browser/editor) and was designed to work on multiple computer platforms.

There were other individuals at CERN and in the broader tech community who provided feedback, support, and development efforts as the World Wide Web began to gain traction, but Cailliau and Pellow were directly involved with Berners-Lee during the early days.

Initial HTML Tags:

While it’s difficult to reconstruct an exact list of the very first HTML tags introduced by Tim Berners-Lee (because documentation from that era is sparse and was not as rigorously versioned as modern specifications), the following tags were among the foundational elements in the earliest incarnations of HTML:

Document Structure:
- <html>, <head>, <title>, <body>
Text Formatting and Structure:
- Headings: <h1>, <h2>, … <h6>
- Paragraph: <p>
- Bold: <b>
- Italic: <i>
- Lists: <ul> (unordered list), <ol> (ordered list), and <li> (list item)
- Preformatted text: <pre>
- Address (for authorship/contact): <address>
Linking and Media:
- Hyperlink: <a href="URL">
- Image embedding: Initially, HTML did not support inline images. The capability to embed images was added with the <img> tag a bit later.
Others:
- <plaintext>: This tag would render the rest of the HTML document as plain text. It was used before the introduction of the <pre> tag.

As mentioned before, this early version of HTML was very basic by today’s standards. However, it set the foundation for the complex and powerful web development framework we have today. Within a short time after its introduction, the rapid expansion and evolution of the web led to many additional tags and features being introduced to HTML.

Here’s a brief overview of the purpose of each tag:

<title>: Specifies the title of the document, displayed in the browser’s title bar or tab.
<nextid>: This was a unique tag used by early web editing tools. It helped allocate a new identifier for a new link.
<a>: Anchor tag, the fundamental hypertext link tag.
<isindex>: Provided a simple way for sending a query to a searchable index on the server.
<plaintext>: Rendered the enclosed text as plain text, without interpreting any included markup.
<listing>: Displayed text in a monospaced font, preserving spaces and line breaks.
<p>: Paragraph tag.
<h1>…<h6>: Header tags, from largest and most important (<h1>) to smallest and least important (<h6>).
<address>: Provided contact information for the author/owner of the document.
<hp1>: An earlier proposed style for emphasized text. Was not widely adopted.
<dl>: Definition list.
<dt>: Definition term within a definition list.
<dd>: Definition of the term within a definition list.
<ul>: Unordered list.
<li>: List item, used within both unordered (<ul>) and ordered (<ol>, which came later) lists.
<menu>: Intended for a list of menu choices.
<dir>: Intended for a directory list.

These tags provided the foundational structure for hypertext documents on the early web. The emphasis was on the ability to structure information and create hyperlinks between documents. Over time, as the web evolved, many more tags were added, and some, like <nextid> and <hp1>, became obsolete.

Evolution Away from SGML:

Over the years, as the web evolved, the ties between HTML and SGML became less pronounced:

XML: The Extensible Markup Language (XML) was introduced as a simplified successor to SGML, meant specifically for web applications. XML provides a way to structure data so it can be shared across different systems, and it has influenced many modern web technologies.
HTML5: With the introduction of HTML5, the language’s definition has moved away from SGML entirely. HTML5 is now defined in terms of the Document Object Model (DOM) rather than any SGML-based syntax.

A Shift to What Web Can Do:

2000s: As the Internet and web technologies grew, there was an increasing demand for web applications with dynamic functionalities. This led to a rise in the use of scripting languages like JavaScript along with HTML and CSS.
2008: WHATWG (Web Hypertext Application Technology Working Group) began working on HTML5 as a response to the need for a modernized version of HTML. Their focus was on ensuring that the web could support the vast array of multimedia and keep up with the rapid technological advancements.
2014: HTML5 was officially finalized and became the W3C Recommendation. This version brought a lot of changes, most notably support for multimedia elements like <video> and <audio>, as well as new form elements, graphic elements (<canvas>), and better support for local offline storage.

Current Usage:

HTML5 and Beyond: As of now, HTML5 is the standard version used worldwide. It’s supported by all major browsers and is crucial for responsive web design, making websites look good on all devices. HTML5 also better integrates with CSS3 and JavaScript to create interactive, dynamic websites and web applications.
Web Components: Modern web development is also seeing a rise in the usage of “Web Components,” which allow developers to create reusable custom elements with their functionality and styles encapsulated away from the rest of the code.
Frameworks and Libraries: While pure HTML is still widely used, many developers today use frameworks (like React, Angular, or Vue.js) that enable more efficient and sophisticated web development. These tools often involve a combination of HTML, CSS, and JavaScript.

The evolution of HTML mirrors the growth and evolution of the web itself. From static documents in the early days to the dynamic, multimedia-rich applications we have today, HTML has been at the core, enabling content to be structured and displayed on the web.

Web Components are a set of web platform APIs that allow developers to create new custom, reusable, and encapsulated HTML tags for web pages and apps. The main technologies behind Web Components are:

Custom Elements: Allow developers to define new types of HTML elements.
Shadow DOM: Encapsulates the styling and the markup for a web component.
HTML Templates: The <template> and <slot> elements enable developers to write markup structures that are not displayed in the rendered page. These can then be reused multiple times as the basis of a web component’s structure.

Here are examples of Web Components:

Material Design Components: These components, often provided by Google or third-party libraries, offer Material Design styled custom elements for buttons, sliders, tabs, and more.
Vaadin Components: Vaadin offers a set of commercial-grade web components for business applications, such as date pickers, grids, and combo boxes.
Polymer Project: Originally developed by Google, the Polymer library makes it easier to create Web Components and has its own set of pre-made components.
Lion Web Components: Made by ING, Lion is a set of highly performant, accessible, and flexible Web Components, which forms a solid foundation for modern web applications.
Elix: A community-driven collection of high-quality web components for common user interface patterns, like carousels or dialog boxes.
Amber Design System: A set of web components following the Amber Design System guidelines, offering components like accordions, badges, and cards.
Components for specific use cases:
- <video-player>: A custom video player with additional controls and settings.
- <modal-dialog>: A customizable modal or popup dialog.
- <image-carousel>: A carousel component to cycle through images.
- <star-rating>: Allows users to provide star ratings for products or services.
Game-related components: Some developers use Web Components to create custom elements for web-based games, like <game-controller>, <player-score>, or <game-board>.

These are just a few examples, and the possibilities are vast. With Web Components, you can essentially create any custom element that suits your application’s needs, ensuring encapsulation and reusability. If you’re interested in diving deeper, there are many online resources and libraries available to help you get started with creating your own Web Components.

Document Object Model (DOM):

Definition: The DOM is a programming interface for web documents. It represents the structure of a document as a tree of objects. Each object corresponds to a part of the document, such as elements and attributes.
Interactive and Dynamic: The DOM can be manipulated using programming languages like JavaScript. This means that web developers can interactively change the content, structure, and style of web pages on the fly, making websites more dynamic and responsive.
Language-Neutral: The DOM is not restricted to HTML. It can also represent XML documents, and its principles can be applied to other types of structured content.

HTML5 and DOM:

HTML5’s Approach: Earlier versions of HTML were defined more as a set of syntactical rules, influenced by SGML. With HTML5, the focus shifted towards defining the behavior of web browsers when they encounter various elements and attributes. In other words, instead of just saying how an HTML document should be written, the specification started detailing how browsers should render and interact with web content.
Parsing and Error Handling: One of the significant departures with HTML5 is its detailed parsing rules and error handling. Before HTML5, browsers often had to guess how to handle malformed HTML, leading to inconsistent rendering across browsers. With HTML5, there are standardized rules for parsing documents and handling errors, ensuring more consistent behavior across different web browsers.
Integration with Web APIs: HTML5 is tightly integrated with various web APIs that operate on the DOM, like the Canvas API for drawing, Video and Audio APIs for multimedia content, and others. These APIs allow developers to create rich, interactive, and multimedia-heavy web content.

Departure from SGML:

Simplified Syntax: Over time, as the web’s needs evolved, there was a desire to make HTML more streamlined and less tied to the complexities of SGML. HTML5’s syntax became simpler, with a focus on being more forgiving and adaptable to the diverse ways developers write code.
No More DTD: In SGML and early HTML, the DOCTYPE declaration referenced a Document Type Definition (DTD), which defined the legal structure of the document. In HTML5, the DOCTYPE is much simpler (<!DOCTYPE html>) and exists mainly for historical reasons and to trigger “standards mode” in browsers. It doesn’t reference a DTD because HTML5 isn’t defined using SGML.

The shift from an SGML-based definition to one centered around the DOM reflects the web’s evolution. As websites became more interactive and user-centric, the need for a dynamic, programmable, and standardized model became paramount. HTML5, with its integration of the DOM and various web APIs, facilitates the creation of modern, interactive, and consistent web experiences.