CPU, that is frequently called just "processor", is an abbreviation for Central Processing Unit. That's the core of any PC or server, since it carries out all of the calculations and logical input/output procedures. Despite the fact that that the performance of a site or an application relies on other things also, including the amount of physical memory or the connection of the web server, the pace at which a certain processor operates determines how soon a program shall be executed. Later-generation processors have several cores that can significantly increase their overall power and efficiency, as each core can take care of a number of processes independently or several cores can take on one process that requires a considerable computing power. Since each and every core functions at a certain speed, this architecture can be seen as a number of independent processors cooperating.