HTML has been in continuous evolution since it was introduced to the Internet in the early 90s. Some features were introduced in specifications and others were introduced in software releases. Also, HTML is defined in a way that is backward compatible with the way user agents handle content. HTML5 is a newer version of the HTML coding language. At the same time, it is more advanced, with new features and changes to improve it. For the most part, both are same. If you know how to code in any older versions of HTML, for the most part you should be good in writing HTML5. But HTML5 has several goals which differentiate it from HTML4. More...HTML4 and HTML5
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