extracting and compressing codes basics HOW?

Hello,

I have examine some extracting and compressing code carefully for understanding extr-compr methods and logic.But I have noticed that I haven’t an information enough to learn with someone else’s extr-compr codes.For this reason I think I must know something about extr-compr before examine that codes.Can you give some information about extr-compr methods and techniques? (simple code with explanatory information can be useful) Thanks...

This page has good information on Huffman coding.

thanks but,I want only some simple example and explanatory knowledge...