APC, which stands for Alternative PHP Cache, is a framework used for caching the compiled source code of a script application, which can boost a database-driven Internet site several times. Each time a PHP webpage is accessed, the script pulls the site content which should be loaded from a database, parses and compiles the program code, and then the result is displayed to the visitor. While this is necessary for websites with routinely changing content, it's a waste of processing time and system resources for an Internet site which does not change, such as an informational portal that shows the same content all the time. Once the pages for such an Internet site are compiled, APC caches them and delivers them every time a website visitor loads them. Since this saves the time to collect content from the database and to parse and compile the program code, the site will load a lot quicker. APC is very useful in particular for scripts with massive source code.