All arithmetical and logical procedures within a computer/server configuration are handled by its Central Processing Unit, or CPU. This hardware component is usually called the "brains" of the computer system too. The rate at which the CPU executes system instructions is generally referred to as its speed and it's measured in Hertz. The speedier the processing unit is, the faster scripts and web apps shall be executed, though the general performance of the latter depends on other things too - the read/write speed of the hard drive, the amount of physical memory, the network connectivity, and many others. All current CPUs have a number of cores, which work together. For that reason, the functionality and the workload a CPU can manage increase, due to the fact that every single core can process different tasks independently and numerous cores can handle 1 task which can't be processed by one core.