All arithmetical and logical functions within a computer/server configuration are tackled by its Central Processing Unit, or CPU. This hardware part is usually called the "brains" of the PC as well. The rate at which the CPU executes system instructions is usually referred to as its speed which is measured in Hertz. The quicker the processing unit is, the faster scripts and web apps will be executed, though the performance of the latter is dependent upon other things also - the read/write speed of the hard disk, the amount of physical memory, the network connection, and so forth. All new CPUs have numerous cores, which work together. For that reason, the functionality and the workload that a CPU can take care of increase, because every core can process a number of tasks separately and several cores can handle one task which can't be processed by one core.