The original HTML was never designed to contain tags for formatting a document. HTML tags were intended to define the content of the document like:

<p>This is a paragraph</p>

<h1>This is a heading</h1>

When color attributes and tags like <font> were added to the HTML 3.2 specification, it started a nightmare for web developers. Development of large web sites where fonts and color information had to be added to every single Web page, became a long, expensive and difficult process.

All formatting can be removed from the HTML document and stored in a separate style sheet in HTML 4.0 .

Because it separates the presentation from the document structure in HTML 4.0, we have what we always needed: Total control of presentation layout without messing up the document content.

Do not use presentation attributes inside your HTML tags if you can avoid it. Start using styles!

Do not use deprecated tags.

XHTML is the "new" HTML. Start writing valid HTML 4.01. Also start writing your tags in lower case. Always close your tag elements. Never end a paragraph without </p>.

The official HTML 4.01 recommends the use of lower case tags.