HTML5 is a markup language used for structuring and presenting content on the World Wide Web.
It was finalized, and published, on 28 October 2014 by the World Wide Web Consortium (W3C).
This is the fifth revision of the HTML standard since the inception of the World Wide Web. The previous version, HTML 4, was standardized in 1997.
It is also an attempt to define a single markup language that can be written in either HTML or XHTML
It extends, improves and rationalizes the markup available for documents, and introduces markup and application programming interfaces (APIs) for complex web applications.
Many features of HTML5 have been designed with low-powered devices such as smartphones and tablets taken in to consideration.
HTML5 adds many new syntactic features. These include the new <video>, <audio> and <canvas> elements, as well as the integration of scalable vector graphics (SVG) content (replacing generic <object> tags) and MathML for mathematical formulas. These features are designed to make it easy to include and handle multimedia and graphical content on the web without having to resort to proprietary plugins and APIs. Other new page structure elements, such as <main>, <section>, <article>, <header>, <footer>, <aside>, <nav> and <figure>, are designed to enrich the semantic content of documents.
New attributes have been introduced, some elements and attributes have been removed and some elements, such as <a>, <cite> and <menu> have been changed, redefined or standardized. The APIs and Document Object Model (DOM) are no longer afterthoughts, but are fundamental parts of the HTML5 specification.