GIF uses the LZW compression scheme, which is held under patent by Unisys Corp. To view an interesting aspect of the controversy involving patentable software, see burnallgifs.org
Making graphics for use in web pages [Prof. D. Allen, Math 696 distance home page]
Graphics Design from Yale Web Design document.
List of Graphics Standards
Another source for Graphics Standards
Screen capture programs:
Adding a touch of style [by Dave Raggett, W3.org]
Introduction to Style Sheets [W3.org]
CSS Home Page [W3.org]
Basic Elements [Math 489, M. Pilant]
Style Example 0 Basic Styles
Style Example 1 Hidden Layers