HTML (HyperText Mark-Up Language) is what is known as a "mark-up language" whose role is to prepare written documents using formatting tags. The tags indicate how the document is presented and how it links to other documents.
HTML is also used for reading documents on the Internet from different computers, thanks to the HTTP protocol, which allows users to remotely access documents stored at a specific address on the network, called a URL.
The World Wide Web (WWW for short), or simply the Web, is the worldwide network formed by all the documents (called "web pages") which are connected to one another by hyperlinks.
Web pages are usually organized around a main page, which acts as a hub for browsing other pages with hyperlinks. This group of web pages joined by hyperlinks and centred around a main page is called a website.
The Web is composed of web pages stored on web servers, which are machines that are constantly connected to the Internet and which provide the pages that users request. Every web page, and more generally any online resource, such as images, video, music, and animation, is associated with a unique address called a URL.
The key element for viewing web pages is the browser, a software program which sends requests to web servers, then processes the resulting data and displays the information as intended, based on instructions in the HTML page.
The most commonly used broswers on the Internet include:
It is important to understand that HTML is a standard, composed of recommendations published by an international consortium: the World Wide Web Consortium (W3C).
The official specifications of HTML describe the language's "instructions" but not how to follow them (the way they are translated by computer programs), so that web pages can be viewed regardless of what the user's operating system or computer architecture may be.
Nevertheless, as detailed as these specifications are, there is still some room for interpretation on the browsers' part, which explains why the same page might be displayed differently from one web browser to another.
What's more, some software publishers add proprietary HTML instructions, which are not found in the W3C's specifications. For this reason, web pages containing such instructions may be displayed just fine in one browser, yet be completely or partially unreadable in others. This is why web pages should follow the W3C's recommendations so that as many people as possible can view them.
HTML was designed by Tim Berners-Lee, at the time a researcher at CERN, beginning in 1989. He officially announced the creation of the Web on Usenet in August 1991. However, it wasn't until 1993 that HTML was considered advanced enough to call it a language (HTML was then symbolically christened HTML 1.0). The web browser used back then was named NCSA Mosaic.
RFC 1866, dated November 1995, represented the first official version of HTML, called HTML 2.0.
After the brief appearance of HTML 3.0, which was never officially released, HTML 3.2 became the official standard on January 14, 1997. The most significant changes to HTML 3.2 were the standardization of tables, as well as many features relating to the presentation of web pages.
On December 18, 1997, HTML 4.0 was released. Version 4.0 of HTML was notable for standardizing style sheets and frames. HTML version 4.01, which came out on December 24, 1999, made several minor modifications to HTML 4.0.