contains file format information on hundreds of different file types and all sorts of other useful programming information; algorithms, source code, specifications, etc.
is the file extension source. Here you'll find a collection of file extensions; many linked to the programs that created the files. This is the FILExt home page.
explains how search engines find and rank web pages, with an emphasis on what webmasters can do to improve their search engine rankings by properly submitting, using better page design, HTML meta tags, and other tips.