HTML---the Hypertext Markup Language---is a simple markup language that describes the structure and contents of web documents. But it’s evolved into a powerful platform over the years.

In its online developer documentation, Netscape in 1996 described HTML as “a set of tags that mark how text is organized and displayed in web browsers such as Netscape Navigator.” Microsoft’s MSDN Library eventually defined it as “a system of marking up or tagging a document so that it can be published on the World Wide Web.”