CPU, that is oftentimes called just "processor", is an abbreviation for Central Processing Unit. This is the core of every personal computer or hosting server, since it carries out each of the calculations and logical input/output procedures. Although the performance of a site or an app is determined by other things too, like the amount of physical memory or the online connectivity of the web server, the speed at which a given processor operates determines how quick an application shall be executed. Later-generation processors have multiple cores that can drastically improve their overall power and efficiency, as each core can handle a number of processes individually or several cores can take care of a single process that requires a sizeable computing power. Due to the fact that each and every core runs at a particular speed, this architecture can be seen as a number of individual processors working together.