CPU, that is frequently called just "processor", is an abbreviation for Central Processing Unit. That is the core of each and every personal computer or server, due to the fact that it runs each of the calculations and logical input/output functions. Even though the performance of a site or an app relies upon other things as well, like the amount of physical memory or the connectivity of the hosting server, the speed at which a particular processor runs determines how quickly an app will be executed. Later-generation processors have numerous cores that can severely increase their overall power and efficiency, as each core can take on several processes individually or a number of cores can control one process that requires a sizeable computing power. Since every core functions at a particular speed, this architecture can be seen as a number of independent processors cooperating.