APC, or Alternative PHP Cache, is a PHP module which caches the output code of database-driven script applications. Dynamic PHP websites hold their content inside a database that is accessed whenever a visitor opens a page. The content that should be shown is retrieved and the code is parsed and compiled prior to it being delivered to the visitor. All these actions need some processing time and involve reading and writing on the server for each page that is accessed. While this cannot be avoided for websites with constantly changing content material, there are various sites that present the same content on many of their pages all of the time - blogs, info portals, hotel and restaurant websites, etc. APC is exceptionally useful for this type of Internet sites since it caches the previously compiled code and displays it any time visitors browse the cached webpages, so the code doesn't have to be parsed and compiled repeatedly. Not only will this minimize the server load, but it'll also boost the speed of any site a few times.