HTML is the predecessor of XHTML. HTML dates back to the early 1990s and late 1980s. Tim Berners-Lee first developed HTML to share document on the web. HTML is a Meta language that is derived from Standard Generalized Markup Language (SGML). SGML is used for creating markup languages such as HTML, XHTML, and XML.
When HTML was first introduced, it was primarily used to exchange reports and research findings at CERN, a physics laboratory in Geneva, Switzerland). By 1993, HTML and its reach was well known. In the same year, CERN released HTML for public use and for governance of the language specifications to an industry group known as the World Wide Web Consortium (W3C). W3C still is responsible for governing HTML, XHTML, and other markup languages. With the introduction of HTTP, Hypertext Transfer Protocol, it was possible for web browsers to request web pages and web servers to serve those pages.
The first version of HTML (HTML 1.0) was introduced in 1993. This version, however, lacked presentation and layout controls that are ubiquitously available to developers today. Consequently, HTML evolved over time with support for new features in each version release. Browser vendors also pushed for new features or they implemented support for their own scripting functionalities without HTML specifications approved by W3C. As a result, different browsers interpreted tags differently and consequently rendering web content in different ways. One of the primary reasons XHTML was introduced to address incompatible HTML scripting implementations.