APC, or Alternative PHP Cache, is a PHP module that caches the output code of database-driven script software apps. Dynamic PHP websites save their content within a database that is accessed whenever a visitor opens a page. The content that should be viewed is gathered and the code is parsed and compiled before it is delivered to the website visitor. All of these actions take some processing time and require reading and writing on the hosting server for each and every page that is loaded. While this cannot be avoided for sites with constantly changing content, there're a lot of Internet sites which present the exact same content on a number of of their webpages all of the time - blogs, info portals, hotel and restaurant sites, etcetera. APC is exceptionally useful for this kind of websites because it caches the already compiled code and shows it every time visitors browse the cached pages, so the code doesn't have to be parsed and compiled again. Not only will this lower the server load, but it'll also raise the speed of any site several times.