All arithmetical and logical functions in a computer/server configuration are addressed by its Central Processing Unit, or CPU. This hardware element is occasionally called the "brains" of the computer as well. The rate at which the CPU runs system instructions is usually referred to as its speed and it is measured in Hertz. The swifter the processing unit is, the more quickly scripts and web programs will be executed, even though the performance of the latter depends upon other things too - the read/write speed of the hard drive, the amount of physical memory, the network connectivity, and so on. All modern CPUs have numerous cores, which work together. Because of this, the overall performance and the workload which a CPU can manage increase, due to the fact that each core can process several tasks independently and numerous cores can handle one task which can't be processed by 1 core.