All arithmetical and logical functions 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 completes system instructions is typically referred to as its speed which is measured in Hertz. The speedier the processing unit is, the faster scripts and web apps will be executed, even though the general 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 forth. All modern CPUs have multiple cores, which work together. Subsequently, the efficiency and the workload a CPU can tackle increase, because every single core can process different tasks individually and numerous cores can handle 1 task that cannot be processed by 1 core.