APC, or Alternative PHP Cache, is a PHP module which caches the output code of database-driven script software applications. Dynamic PHP websites save their content inside a database that is accessed whenever a visitor loads a page. The content which has to be shown is gathered and the code is parsed and compiled before it's delivered to the website visitor. All these actions take some processing time and require reading and writing on the hosting server for each page that is accessed. While this can't be avoided for sites with constantly changing content, there're many sites which offer the exact same content on a lot of of their pages at all times - blogs, informational portals, hotel and restaurant sites, and many others. APC is very useful for this kind of Internet sites because it caches the previously compiled code and shows it each time visitors browse the cached pages, so the code doesn't have to be parsed and compiled again. Not only will this minimize the server load, but it will also raise the speed of any site several times.