Tim Berners-Lee, a physicist working at CERN, invented HTML in the late 1980s as a way for researchers to share and collaborate on information. The earliest versions of HTML included basic markup tags but lacked features like tables. Subsequent versions in the 1990s, such as HTML 3.2, HTML 4, and HTML 4.01, added support for additional elements, tags, and features to enhance the functionality and capabilities of HTML. HTML is not a programming language but a markup language that uses tags to define the structure and layout of web pages.