APC, or Alternative PHP Cache, is a PHP module which caches the output code of database-driven script software applications. Dynamic PHP websites store their content inside a database which is accessed whenever a visitor loads a webpage. The content which should be viewed is gathered and the code is parsed and compiled before it's delivered to the site visitor. All of these actions need some processing time and include reading and writing on the server for each and every page which is loaded. While this can't be avoided for Internet sites with regularly changing content material, there are various Internet sites that feature the exact same content on many of their pages at all times - blogs, info portals, hotel and restaurant websites, etcetera. APC is very useful for this kind of Internet sites since it caches the previously compiled code and displays it each time visitors browse the cached pages, so the code doesn't need to be parsed and compiled repeatedly. This will not only reduce the server load, but it'll also increase the speed of any site several times.