HTTP Compression is a very simple and effective way to save bandwidth and improve web applications performance over network.
Output compression is basically a process of compressing web servers response by using a loss-less compression algorithm called gzip.
This technique is fairly modern and almost all modern browsers honor it, however if a page is requested from a browser which does not send a header
Accept-Encoding: gzip,deflate then the response comes back uncompressed.
In Apache under Ubuntu OS this is fairly simple.
Enable mod_deflate in Apache2
sudo a2enmod deflate
configure /etc/apache2/httpd.conf mod_deflate by adding content mentioned below.
Restart apache to anable the changes
sudo apachectl graceful
There is another powerfull apache module called
mod_gzip which can precompress output as well.
Hope this helps.