On 28 October 2014, the W3C officially published HTML5 as a Web standard (or recommendation of HTML5). HTML5 is the fifth major revision of the format used to build Web pages and applications.
HTML5 contains powerful capabilities for Web-based applications with more interaction, video support, graphics, more styling effects, and a full set of APIs. HTML5 adapts to any device, be it a desktop, mobile, tablet, or television device. HTML5 is an open platform developed under royalty free licensing terms.
People use the term HTML5 in two ways:
to refer to a set of technologies that together form the future Open Web Platform. These technologies include HTML5 specification, CSS, SVG, MathML, Geolocation, XMLHttpRequest, 2D Context, Web Fonts (WOFF) and others. The boundary of this set of technologies is informal and changes over time.
to refer to the HTML5 specification, which is, of course, also part of the Open Web Platform.
Although it would be great if people used one term to refer to the specification and another term to refer to the set of specifications, in practice people use the term both ways.
When HTML5 became a Web standard, Tim Berners-Lee, Web inventor and W3C Director said:
"Today we think nothing of watching video and audio natively in the browser, and nothing of running a browser on a phone. We expect to be able to share photos, shop, read the news, and look up information anywhere, on any device. Though they remain invisible to most users, HTML5 and the Open Web Platform are driving these growing user expectations."