APC, or Alternative PHP Cache, is a PHP module that caches the output code of database-driven script apps. Dynamic PHP Internet sites store their content within a database which is accessed whenever a visitor opens a webpage. The content that needs to be displayed is gathered and the code is parsed and compiled prior to it being delivered to the website visitor. These actions take some processing time and require reading and writing on the server for each and every page that is accessed. While this cannot be avoided for Internet sites with regularly changing content material, there're many Internet sites that feature the same content on many of their pages all the time - blogs, info portals, hotel and restaurant Internet sites, and many others. APC is really useful for this kind of websites since it caches the previously 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. This will not only lower the server load, but it will also raise the speed of any Internet site many times.