All arithmetical and logical procedures in a computer/server configuration are handled by its Central Processing Unit, or CPU. This hardware part is occasionally called the "brains" of the computer system too. The rate at which the CPU completes system instructions is also referred to as its speed and it's measured in Hertz. The quicker the processing unit is, the more quickly scripts and web programs shall be executed, though the general performance of the latter is determined by other things too - the read/write speed of the hard disk, the amount of physical memory, the network connectivity, and so forth. All current CPUs have several cores, that work together. As a result, the efficiency and the workload a CPU can manage increase, since each core can process a number of tasks individually and numerous cores can handle one task that can't be processed by 1 core.