PHP's native get_browser() function parses this file and provides you with a complete set of information about every browser's details. But it requires the path to the browscap.ini file to be specified in the php.ini browscap directive which is flagged as PHP_INI_SYSTEM. That means in most shared hosting environments you cannot edit the php.ini file.

Browscap is a standalone class for both PHP4 and PHP5 that gets around the limitations of get_browser() and manages the whole thing. It offers methods to update, cache, adapt and get details about every supplied user agent on a standalone basis.

Sometimes you need to visit some project site to read about simple php functions like "get_browser()"