This function simply allows you to get the current version of Apache running on the machine - if it’s installed, of course. Could be useful for checking requirements.

$apache_v = apache_get_version();
// Result will vary of course. Here's one example:
// Apache/2.2.11 (Ubuntu) PHP/5.2.6-3ubuntu4.1 with Suhosin-Patch
See the manual entry for apache_get_version()