CPU, that's oftentimes called just "processor", is an abbreviation for Central Processing Unit. This is the core of each computer or hosting server, due to the fact that it performs all the calculations and logical input/output functions. Even though the performance of an Internet site or an app relies on other things also, like the amount of physical memory or the connection of the hosting server, the speed at which a given processor works determines how quickly an application shall be executed. Later-generation processors have several cores that can considerably improve their overall power and efficiency, since every single core can take on numerous processes independently or a few cores can take on one process which requires a significant processing power. Because every core works at a particular speed, this architecture can be seen as a few independent processors cooperating.