HTML, short for HyperText Markup Language, was developed by Tim Berners-Lee in 1991. It is a markup language that structures the content on a webpage by using tags to define different elements such as headings, paragraphs, images, and links. HTML provides a hierarchical structure to organize information and facilitates the presentation of content. With HTML, developers can define the layout, formatting, and visual aspects of a webpage. It is the backbone of every website, serving as the building blocks on which all other components are layered.