All arithmetical and logical operations in a computer/server configuration are addressed by its Central Processing Unit, or CPU. This hardware element is sometimes called the "brains" of the computer also. The rate at which the CPU runs system instructions is commonly referred to as its speed and it's measured in Hertz. The swifter the processing unit is, the speedier scripts and web programs will be executed, even though the efficiency of the latter is dependent upon other things too - the read/write speed of the hard disk drive, the amount of physical memory, the network connectivity, and so forth. All current CPUs have several cores, which work together. For that reason, the overall performance and the workload which a CPU can handle increase, since every single core can process various tasks independently and a number of cores can handle one task which can't be processed by 1 core.