All arithmetical and logical operations in a computer/server configuration are addressed by its Central Processing Unit, or CPU. This hardware element is usually called the "brains" of the computer system as well. The pace at which the CPU executes system instructions is usually referred to as its speed and it's measured in Hertz. The quicker the processing unit is, the speedier scripts and web programs will be executed, though the performance of the latter depends on other things also - the read/write speed of the hard disk, the amount of physical memory, the network connectivity, and so forth. All new CPUs have a number of cores, that work together. For that reason, the efficiency and the workload that a CPU can take care of increase, as each core can process various tasks individually and a number of cores can handle 1 task that can't be processed by one core.
