The document discusses HTML color codes. Colors are created by combining levels of red, green, and blue light, with each color value ranging from 00 to FF in hexadecimal notation. This provides over 16 million possible colors. Common colors like black, white, red, green, blue etc are given with their hexadecimal and RGB values. Shades of gray are also shown, created by using equal levels of the three primary colors. Earlier, 216 "web safe" colors were defined to work on all systems supporting 256 colors.