HTML (HyperText Markup Language) was first proposed in 1989 by Tim Berners-Lee, a British computer scientist. He was working at CERN (the European Organization for Nuclear Research) when he came up with the idea of a system that could link documents together over the internet using hypertext.

Timeline:

• 1989: Tim Berners-Lee proposed the concept of HTML and the World Wide Web.
• 1991: The first version of HTML was introduced to the public, which was a simple language with just 18 tags for creating basic webpages.
• 1995: HTML became more standardized and expanded with the release of HTML 2.0.

Since then, HTML has evolved significantly with newer versions such as HTML 4.01 (1999) and HTML5 (2014), which brought many enhancements for multimedia, mobile devices, and richer web experiences.