Markup languages allow for annotating documents in a way that is distinguishable from the text. In 1969, Charles Goldfarb led the creation of GML, the first markup language. In 1974, Goldfarb invented SGML, the standard generalized markup language, which formed the basis for languages like XML and HTML. SGML became an international standard in 1986 and was used to design XML. Key languages descended from SGML include HTML, created by Tim Berners-Lee in 1991 to define web pages, and XML, developed in 1996 as a simplified version of SGML to share data on the web.