In this tutorial I will describe how to install and configure mod_deflate on a lighttpd 1.4 web server on Debian Etch. mod_deflate is included by default in lighttpd 1.5, but not in 1.4 where mod_compress is used instead. The advantage of mod_deflate over mod_compress is that it can compress static and dynamic files (such as PHP files), whereas mod_compress can compress static files only. The lighttpd version coming with Debian Etch is 1.4.13, so we have to patch it to support mod_deflate. mod_deflate allows lighttpd to compress files and deliver them to clients (e.g. browsers) that can handle compressed content which most modern browsers do. With mod_deflate, you can compress HTML, text or XML files to approx. 20 - 30% of their original sizes, thus saving you server traffic and making your modem users happier.