CPU, that's sometimes called just "processor", is an abbreviation for Central Processing Unit. That is the core of each PC or hosting server, due to the fact that it performs all of the calculations and logical input/output operations. Despite the fact that that the performance of a website or an application depends on other things too, including the amount of physical memory or the connection of the server, the speed at which a particular processor operates determines how fast a program shall be executed. Later-generation processors have several cores which can significantly increase their overall power and efficiency, because each and every core can handle several processes separately or several cores can take care of one process that requires a considerable computing power. Since each core works at a specific speed, this architecture can be viewed as a number of individual processors cooperating.