CPU, that is often called just "processor", is an abbreviation for Central Processing Unit. That is the core of each computer or hosting server, since it executes all of the calculations and logical input/output procedures. Though the performance of a site or an application depends on other things also, like the amount of physical memory or the connection of the hosting server, the speed at which a certain processor performs determines how fast an application shall be executed. Later-generation processors have a number of cores which can severely increase their overall power and efficiency, because each core can control a variety of processes independently or several cores can take care of one process which needs a sizeable computing power. Due to the fact that each and every core operates at a certain speed, this architecture can be seen as numerous individual processors working together.