APC, which means Alternative PHP Cache, is a framework used for caching the compiled source code of a script application, which can boost a database-driven website several times. When a PHP page is accessed, the script pulls the website content which has to be displayed from a database, parses and compiles the program code, and the result is shown to the visitor. While this is necessary for Internet sites with regularly changing content, it is a complete waste of processing time and resources for a site which does not change, for example an informational portal that shows the same content at all times. Once the web pages for such a website are compiled, APC caches them and delivers them whenever a visitor loads them. As this saves the time to obtain content from the database and to parse and compile the program code, the site will load significantly quicker. APC is really useful in particular for scripts with massive source code.