All arithmetical and logical functions within a computer/server configuration are tackled by its Central Processing Unit, or CPU. This hardware component is sometimes called the "brains" of the PC as well. The rate at which the CPU completes system instructions is generally referred to as its speed which is measured in Hertz. The speedier the processing unit is, the quicker scripts and web applications will be executed, though the performance of the latter is determined by other things too - the read/write speed of the hard disk drive, the amount of physical memory, the network connection, and many others. All current CPUs have multiple cores, which work together. Thus, the overall performance and the workload which a CPU can take care of increase, because every single core can process various tasks separately and numerous cores can handle 1 task which cannot be processed by a single core.