All arithmetical and logical operations within a computer/server configuration are tackled by its Central Processing Unit, or CPU. This hardware component is occasionally called the "brains" of the PC too. The rate at which the CPU runs system instructions is generally referred to as its speed and it is measured in Hertz. The quicker the processing unit is, the faster scripts and web applications shall be executed, even though the performance of the latter is determined by other things also - the read/write speed of the hard disk, the amount of physical memory, the network connectivity, and so on. All modern CPUs have several cores, which work together. Thus, the functionality and the workload which a CPU can tackle increase, as each and every core can process different tasks individually and several cores can handle 1 task that cannot be processed by one core.