HTML stands for HyperText Markup Language, English expression meaning "Hypertext Markup Language". It consists of a markup language used to produce web pages, which allows the creation of of documents that can be read on virtually any type of computer and transmitted over the Internet.
To write HTML documents you need nothing more than a simple text editor and knowledge of the codes that make up the language. The codes (known as tags) serve to indicate the function of each element of the web page. Tags work as text formatting commands, forms, links (links), images, tables, among others.
You browsers (browsers) identify the tags and present the page as specified. An HTML document is plain text, which can be edited in Notepad (Windows) or Text Editor (Mac) and turned into hypertext.
The HTML language was created by Tim Barners Lee in the 1990s. Language specifications are controlled by the W3C (World Wide Web Consortium).
Evolved versions of HTML include XHTML (a more rigorously syntaxd, XML-based language) and HTML5 (fifth version of HTML that brings new features, mainly the manipulation of graphic and multimedia content).
See also the meaning of HTTP.