Short for HyperText Markup Language, the authoring language used to create documents on the World Wide Web. HTML is similar to SGML (Standard Generalized Markup Language), although it is not a strict subset. HTML defines the structure and layout of a web document by using a variety of tags and attributes. The correct structure for an HTML document starts with <HTML><HEAD> (enter here what document is about), <BODY> and ends with </BODY></HTML>. All the information you'd like to include in your web page fits in between the <BODY> and </BODY> tags.
There are hundreds of other tags used to format and layout the information in a web page. Tags are also used to specify hypertext links. These allow web developers to direct users to other web pages with only a click of the mouse on either an image or word(s).
Source: https://www.webopedia.com/