CPU, that's often called just "processor", is an abbreviation for Central Processing Unit. That is the core of each and every personal computer or server, since it runs all of the calculations and logical input/output functions. Even though the performance of an Internet site or an app relies on other things as well, such as the amount of physical memory or the connection of the server, the speed at which a certain processor operates determines how quick a program shall be executed. Later-generation processors have a number of cores that can drastically improve their overall power and efficiency, due to the fact that each core can take on numerous processes separately or a few cores can deal with a single process which needs a considerable processing power. Since each core functions at a particular speed, this architecture can be seen as a number of independent processors working together.