APC, or Alternative PHP Cache, is a PHP module which caches the output code of database-driven script software applications. Dynamic PHP Internet sites save their content inside a database which is accessed whenever a visitor loads a webpage. The content that needs to be viewed is gathered and the code is parsed and compiled before it is delivered to the site visitor. All of these actions need some processing time and include reading and writing on the web server for every single page that is accessed. While this can't be avoided for sites with constantly changing content, there are many Internet sites that present the same content on a number of of their webpages at all times - blogs, info portals, hotel and restaurant Internet sites, etc. APC is extremely useful for this kind of websites since it caches the previously compiled code and displays it when visitors browse the cached webpages, so the code does not need to be parsed and compiled again. Not only will this greatly reduce the server load, but it'll also increase the speed of any website many times.