APC, which is an acronym for Alternative PHP Cache, is a framework used for caching the compiled source code of a given script application, that could speed up a database-driven Internet site several times. Each time a PHP page is accessed, the script pulls the content that has to be shown from a database, parses and compiles the code, then the result is displayed to the visitor. While this is necessary for Internet sites with frequently changing content, it's a waste of processing time and resources for an Internet site which does not change, such as an informational portal which shows the very same content on a regular basis. Once the webpages for such a website are compiled, APC caches them and delivers them any time a visitor accesses them. As this saves the time to get content from the database and to parse and compile the program code, your website will load a lot faster. APC is very useful particularly for scripts with massive source code.