Bandwidth is finite, and saving it can save money as well as speed up access to web resources. One method to save on bandwidth is to use HTTP Compression. HTTP Compression is built into most web servers and browsers and can improve site performance by reducing the amount of time required to transfer data between the server and the client. To achieve this, the data is compressed.

The amount of compression varies with file types. HTML, XML and other text file types will compress quite a lot, while other file types such as JPEG, GIF and ZIP will not. This is due to the fact that they are already compressed and connot be compressed any further. To enable HTTP Compression in IIS 6 open up the Internet Serivces Manager MMC and enter the Default Website Properties (or the properties of the website you wich to enable compression on) and select the Service tab. Check the two boxes under HTTP Compression and enter the path to a temp directory.

The temp directory must be on an NTFS partition and if you wish to set a size limit, set it equal to 2 times the size of the website. One final note. IIS will cache the compressed data for a time, however, enabling compression will increase CPU usage so you may want to monitor this once you have enabled it. If you need to disable it simply uncheck the two boxes. Also if you are still running IIS 5 you will have to purchase some 3rd party software as it does not have built in compression.