All arithmetical and logical functions within a computer/server configuration are handled by its Central Processing Unit, or CPU. This hardware component is sometimes called the "brains" of the PC also. The rate at which the CPU runs 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 applications will be executed, though the overall performance of the latter is determined by other things as well - the read/write speed of the hard drive, the amount of physical memory, the network connection, and many others. All new CPUs have several cores, that work together. Subsequently, the effectiveness and the workload which a CPU can manage increase, due to the fact that every single core can process several tasks individually and numerous cores can handle 1 task that cannot be processed by a single core.