Before the HTML4 specification, many Web designers used uppercase type for HTML element and attribute names to visually distinguish them from mixed-case content. Beginning with HTML4, authors were encouraged to use lowercase names for compatibility with XML syntax rules. Now, in HTML5 age remember that in strict XHTML and HTML5, lowercase names are required.
The specification requires all meta elements to appear within the first 512 bytes of a document. That’s why put character encoding (and other meta) elements right after the tag.
It incorporates and continues to use almost all the markup associated with HTML4 and XHTML. It’s minds also that all the elements and attributes deprecated in HTML4 and XHTML are not be part of HTML5.
All elements like sections, divisions, headings, footers, paragraphs, lists, tables, block quotes, address blocks are all block elements.
The specification does not require quotation marks around attribute values if the meaning is unambiguous, however older versions of HTML do require them. That’s why it’s better to enclose attribute values in quotes.
New specification allows the anchor element to enclose any other content as long as that content does not itself contain interactive items—links or buttons that are sensitive to users actions.
The video element (new in HTML5) is will be used to play videos or movies. Code belowe shows you how to insert a video element with a fallback to use an Adobe Flash plugin if user old browser does not support HTML5 video.
<video src="myracing.mp4" width="555" height="280" poster="screenshot5.jpg" controls>
<!-- Here put your Flash player code -->
<object...>
<param.../>
<param.../>
<embed...>
</embed>
</object>
<!-- end Flash player code -->
</video>
Because some older browser like IE8 doesnt’t support new elements try out HTML5 Shiv (created by Remy Sharp, http://code.google.com/p/html5shiv), a JavaScript script which you can include on your HTML5 code to helps browsers work properly with HTML5.