CPU, that's sometimes called just "processor", is an abbreviation for Central Processing Unit. That is the core of any laptop or computer or hosting server, due to the fact that it carries out all of the calculations and logical input/output procedures. Even though the performance of a site or an application is determined by other things too, like the amount of physical memory or the online connectivity of the web server, the rate at which a given processor operates determines how quickly a program will be executed. Later-generation processors have a number of cores that can considerably improve their overall power and efficiency, as each core can take care of a number of processes individually or a number of cores can control a single process that needs a significant computing power. Since every single core runs at a certain speed, this architecture can be looked at as a few independent processors cooperating.