HTML5 is a software solution stack that defines the properties and behaviours of web page content by implementing a markup-based pattern to it.
HTML5 is the fifth and current major version of HTML, and subsumes XHTML. The current standard, the HTML Living Standard is developed by WHATWG, which is made up of the major browser vendors (Apple, Google, Mozilla, and Microsoft), with the Living Standard also existing in an abridged version.
HTML5 was first released in public-facing form on 22 January 2008, with a significant update and "W3C Recommendation" status in October 2014.
Its goals were to improve the language with support for the latest multimedia and other new features; to keep the language both easily readable by humans and consistently understood by computers and devices such as web browsers, parsers, etc., without XHTML's rigidity; and to remain backwards-compatible with older software.
HTML5 is intended to subsume not only HTML 4, but also XHTML 1 and DOM Level 2 HTML.
You can read more at https://en.wikipedia.org/wiki/HTML5
Html5 local storage in this blog, I will explain what local storage is and show an example of how to use it in your web application
The Wikipedia definition of HTML5 is a markup language used for structuring and presenting content on the World Wide Web.