APC, which is an acronym for Alternative PHP Cache, is a framework used for caching the compiled source code of a script application, which can speed up a database-driven site several times. Each time a PHP page is accessed, the script pulls the website content that needs to be shown from a database, parses and compiles the program code, then the result is shown to the website visitor. While this is necessary for websites with constantly changing content, it is a waste of processing time and system resources for an Internet site that doesn't change, such as an informational portal that displays the exact same content on a regular basis. Once the webpages for such a site are compiled, APC caches them and delivers them whenever a website visitor opens them. Since this saves the time to collect content from the database and to parse and compile the code, the Internet site will load considerably faster. APC is really efficient particularly for scripts with massive source code.