I wasn't much aware of HTTP compression though I heard the term often. Thanks to a nice article written by Martin Brown, I was able to get a basic understanding as well as how to get Apache and IIS servers configured to use HTTP compression.
HTTP compression is an mechanism to utilize the available bandwidth effectively. HTTP protocol data is compressed before it is sent from the server. No specific configuration is required at the client side and server configuration is also relatively simple.
If you are involved in web performance testing, It would be worthwhile to get some knowledge on HTTP compression.