It is the fifth revision of the HTML standard (created in 1990 and standardized as HTML4 since 1997) and is in development since October 2011. Its main objectives were to improve the language with support for the latest multimedia issues while maintaining the readability of people and well understood by computers and devices (web browsers, parsers, etc.).
HTML5 aims to add not only HTML4 but also XHTML1 and DOM2HTML (especially JavaScript). Following its immediate predecessors HTML 4.01 and XHTML 1.1, HTML5 is a response to the observation that HTML and XHTML commonly used on the World Wide Web are a mix of features introduced by different specifications, along with the different features brought by the software, browsers, and many syntax errors in existing web docs. Thus, HTML5 becomes an attempt to define a single markup language that can be written in any of the HTML and / or XHTML syntax.
It includes detailed processing models to encourage more interoperable deployments; expands, improves and streamlines web document availability and introduces markup and application programming interfaces (APIs) for complex web applications. For these reasons, HTML5 is a potential candidate for mobile platform applications. Many features of HTML5 have been created because you will need to be able to run them on devices such as smartphones or tablets.