Add these lines to the .htaccess file.
AddOutputFilterByType DEFLATE text/plain AddOutputFilterByType DEFLATE text/html AddOutputFilterByType DEFLATE text/xml AddOutputFilterByType DEFLATE text/css AddOutputFilterByType DEFLATE application/xml AddOutputFilterByType DEFLATE application/xhtml+xml AddOutputFilterByType DEFLATE application/rss+xml AddOutputFilterByType DEFLATE application/javascript AddOutputFilterByType DEFLATE application/x-javascript
Or you can specifically compress certain types of files.
The following code will compress only css and javascript files.
<Files *.css> SetOutputFilter DEFLATE </Files> <Files *.js> SetOutputFilter DEFLATE </Files>
To check whether the compression is working, use Google PageSpeed or Yahoo YSlow
A more detailed explanation is given in http://betterexplained.com/articles/how-to-optimize-your-site-with-gzip-compression/
