APC, which stands for Alternative PHP Cache, is a framework used for caching the compiled source code of a given script app, which can speed up a database-driven Internet site several times. Any time a PHP page is accessed, the script pulls the website content which needs to be displayed from a database, parses and compiles the program code, and the result is shown to the site visitor. While this is necessary for Internet sites with constantly changing content, it's a total waste of processing time and system resources for a site which does not change, for example an informational portal that displays identical content at all times. As soon as the pages for such an Internet site are compiled, APC caches them and delivers them every time a visitor opens them. As this saves the time to get content from the database and to parse and compile the program code, your Internet site will load considerably faster. APC is very efficient particularly for scripts with large source code.