How to support HTML4 and HTML5?

Question

So, I have a complete website written in HTML4 format with support for CSS2 / CSS3, i.e. mostly using most supported CSS3.

I want to update the site to support HTML5 - but a little confused [using Visual Studio 2010 / ASP.NET MVC, etc.], how can I support HTML4 and HTML5?

Do I need to rewrite the entire site in HTML5 or? A little vague, how to support HTML4 and HTML5?

Answer 1

You do not need anything.

HTML5 is an umbrella term for a set of loosely coupled client-side functions supported by the latest browsers.
You can simply use any functions that you like.

, , - , .
Modernizr.

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HTML5 HTML4.
shiv, IE lt; 9.
Modernizr .

Answer 2

HTML5 ? , , , .. ? , HTML4- HTML5.

, HTML5 Intellisense Visual Studio 2010 2008.