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HTML5 is a latest version of HTML in web designing.Its core aims have been to improve the language with support for the latest multimedia while keeping it easily readable by humans and consistently understood by computers and devices.It includes detailed processing models to encourage more interoperable implementations; it extends, improves and rationalises the markup available for documents, and introduces markup and application programming interfaces(APIs) for complex web applications.For the same reasons, HTML5 is also a potential candidate for cross-platform mobile applications. Many features of HTML5 have been built with the consideration of being able to run on low-powered devices such as smartphones and tablets.

In particular, HTML5 adds many new syntactical features. These include the new

HTML5 is still under-development and the hottest one in web-designing.

You can try more sites build up in html5 to have a closer look about it and know the difference.