CPU, which is frequently called just "processor", is an abbreviation for Central Processing Unit. That is the core of each laptop or computer or server, because it performs all of the calculations and logical input/output operations. Although the performance of a website or an application relies on other things as well, like the amount of physical memory or the online connectivity of the web server, the speed at which a specific processor works determines how quick an application will be executed. Later-generation processors have multiple cores that can seriously improve their overall power and efficiency, since each and every core can control several processes independently or several cores can control a single process which needs a substantial processing power. Because every single core functions at a specific speed, this architecture can be seen as a few separate processors working together.