HTML5 Syntax

The HTML 5 language has a “custom” HTML syntax that is compatible with HTML 4 and XHTML1 documents published on the Web, but is not compatible with the more esoteric SGML features of HTML 4. HTML 5 does not have the same syntax rules as XHTML where we  needed lower case tag names, quoting our attributes,an attribute had to have a value and to close all empty elements.

But HTML5 is coming with lots of flexibility and would support the followings:

1. Uppercase tag names.
2. Quotes are optional for attributes.
3. Attribute values are optional.
4. Closing empty elements are optional.

A consequent use of style, makes it easier for others to understand and use your HTML.
In the future, programs like XML readers, may want to read your HTML.
Using a well-formed “close to XHTML” syntax, can be smart.