Hypertext markup language (HTML) is the fundamental form of computer code upon which websites on the world wide web (WWW) are based. HTML is known as a scripting language that uses standard English words encased in brackets, known as tags, to indicate to a computer's browser the various formatting options for displaying content. This can include text formatting, such as bold, italics, and indentation features, as well as display options for images, video, and audio files, or other interactive features on websites. While HTML designs initially started out as very simple website pages in the early 1990s, hypertext markup language has since undergone several revisions and expansions to accommodate the new capabilities of computer browsers and high-speed Internet connections. The first update to standards for HTML designs took place at the end of 1995 when HTML 2.0 standards allowed for new features on websites, such as tables for text and images, and image maps; as of the year 2000, however, HTML designs had reached a revision stage of 4.01, allowing for browsers to more efficiently display offshoots of HTML coding schemes such as extensible markup language (XML).
While website design as of 2011 remains firmly founded in the principles of HTML code, many variations on working with HTML now exist that also use scripting languages based on English words encased in tags, which a browser interprets to display content. The popular variations on HTML designs using other coding schemes include XML, cascading style sheets (CSS), dynamic HTML (DHTML), and more. As each new coding scheme was adopted by the software development companies that release versions of popular computer browsers, the functionality of websites and ease of customizing them has become greater.
XML's main advantage is that it offers someone who is working with HTML the ability to specify how elements on a webpage are displayed based on their content instead of the form in which they are stored, which makes duplicating a layout from one page to another much easier than with standard HTML designs. CSS offers a similar advantage with text displays using a small amount of HTML code that accesses CSS files stored on the server onto which a website is loaded. This makes editing the size, font, and color of text for all the pages on a website much easier, by editing a small number of CSS files instead of each webpage individually.
Learning HTML can start out as a simple process and quickly become complex once someone encounters all of the various new coding schemes that are being linked to HTML designs to enhance a website's look and appeal. Each coding scheme may also only have limited support on various types of browsers, where one will display its code correctly and another may not. It is also required that plug-ins, or small programs embedded within a browser, be downloaded to a personal computer for some HTML design elements to work, such as vector-based animation. For this reason, working with HTML should first focus on a comprehensive view of the 4.01 standards detailed in modern web design books and online tutorials. Referencing the latest version of HTML standards allows a designer to create a site that offers the most interactivity, as well as having the likelihood of being consistently displayed on all modern computer browsers built to support the standard.