All arithmetical and logical operations inside a computer/server configuration are handled by its Central Processing Unit, or CPU. This hardware part is oftentimes called the "brains" of the computer system too. The rate at which the CPU runs system instructions is also referred to as its speed and it is measured in Hertz. The quicker the processing unit is, the quicker scripts and web applications shall be executed, although the general performance of the latter depends upon other things too - the read/write speed of the hard disk drive, the amount of physical memory, the network connectivity, etc. All new CPUs have several cores, that work together. For that reason, the efficiency and the workload which a CPU can take care of increase, since every core can process different tasks individually and a number of cores can handle 1 task that can't be processed by 1 core.