All arithmetical and logical operations inside a computer/server configuration are addressed by its Central Processing Unit, or CPU. This hardware element is usually called the "brains" of the PC as well. The pace at which the CPU completes system instructions is generally referred to as its speed and it's measured in Hertz. The speedier the processing unit is, the quicker scripts and web programs shall be executed, though the efficiency of the latter is dependent upon other things also - the read/write speed of the hard drive, the amount of physical memory, the network connectivity, and so on. All modern CPUs have a number of cores, which work together. Because of this, the efficiency and the workload a CPU can tackle increase, because each and every core can process a number of tasks individually and numerous cores can handle one task that can't be processed by a single core.