APC, or Alternative PHP Cache, is a PHP module that caches the output code of database-driven script software apps. Dynamic PHP sites save their content inside a database that is accessed whenever a visitor loads a page. The content that needs to be shown is gathered and the code is parsed and compiled before it is delivered to the visitor. These actions need some processing time and require reading and writing on the server for every single page which is loaded. While this cannot be avoided for Internet sites with regularly changing content material, there are many sites that present the same content on a number of of their pages at all times - blogs, info portals, hotel and restaurant sites, and many others. APC is extremely useful for this kind of Internet sites as it caches the already compiled code and shows it whenever visitors browse the cached pages, so the code does not need to be parsed and compiled all over again. Not only will this lower the server load, but it will also boost the speed of any website a few times.