CPU, which is frequently called just "processor", is an abbreviation for Central Processing Unit. That is the core of each computer or web server, as it carries out all the calculations and logical input/output procedures. Even though the performance of a website or an app is determined by other things too, like the amount of physical memory or the connectivity of the hosting server, the pace at which a particular processor operates determines how quickly a program will be executed. Later-generation processors have a number of cores which can severely increase their overall power and efficiency, because every core can handle several processes individually or a few cores can take care of a single process which requires a considerable computing power. As every core works at a specific speed, this architecture can be seen as numerous individual processors cooperating.