<?php if (substr_count($_SERVER['HTTP_ACCEPT_ENCODING'], 'gzip')) ob_start("ob_gzhandler"); else ob_start(); ?>

If you are using Apache Web Server, there are also has two additional compression options:

• mod_deflate is easier to set up and is standard.
• mod_gzip is more powerful: you can pre-compress content.

Deflate is quick and works; use mod_gzip for more control. In either case, Apache checks if the browser sent the “Accept-encoding” header and returns the compressed or regular version of the file. However, some older browsers may have trouble and there are special directives you can add to correct this.