All arithmetical and logical operations inside a computer/server configuration are addressed by its Central Processing Unit, or CPU. This hardware part is typically called the "brains" of the PC as well. The rate at which the CPU runs system instructions is usually referred to as its speed and it is measured in Hertz. The swifter the processing unit is, the speedier scripts and web programs shall be executed, though the general performance of the latter depends upon other things as well - the read/write speed of the hard disk drive, the amount of physical memory, the network connection, etc. All new CPUs have several cores, that work together. As a result, the efficiency and the workload which a CPU can handle increase, as every core can process different tasks independently and a number of cores can handle a single task which cannot be processed by 1 core.