HTML References - Many reference guides and tutorials for the novice to experienced webmaster. The Compendium of HTML Elements - A description of the abbr tag, attributes, arguments and examples. Testing Hexadecimal Color Combos - Includes a utility for previewing color schemes and background images for use in HTML documents, advice about choosing colors and backgrounds and an explanation of hexadecimal numbers. Slacker's Guide to HTML - Large list of HTML tags with links leading to their explanations. Bare Bones Guide to HTML - HTML 4.0 guide and explanation of commonly used tags.
Translated versions are also available.
Index Dot HTML - The advanced HTML reference. Repositories and references for technical information about the HTML and CSS languages. HTML Tag and Color Test Page - See how various HTML tags will display text in your browser. A list of HTML color names and color hexadecimal numbers. Has search capability and is cross referenced with resources from around the web.