All arithmetical and logical operations within a computer/server configuration are tackled by its Central Processing Unit, or CPU. This hardware part is usually called the "brains" of the personal computer as well. The rate at which the CPU executes system instructions is typically referred to as its speed and it's measured in Hertz. The faster the processing unit is, the more quickly scripts and web programs shall be executed, although 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 connection, and so forth. All modern CPUs have numerous cores, that work together. For that reason, the functionality and the workload which a CPU can tackle increase, because each core can process various tasks independently and numerous cores can handle 1 task which can't be processed by a single core.