All arithmetical and logical functions inside 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 too. The rate at which the CPU executes system instructions is usually referred to as its speed which is measured in Hertz. The quicker the processing unit is, the more quickly scripts and web programs shall be executed, although the performance of the latter depends on other things as well - the read/write speed of the hard disk, the amount of physical memory, the network connectivity, etc. All current CPUs have numerous cores, that work together. Because of this, the overall performance and the workload a CPU can tackle increase, because every core can process different tasks independently and a number of cores can handle a single task which cannot be processed by 1 core.