All arithmetical and logical operations in a computer/server configuration are handled by its Central Processing Unit, or CPU. This hardware component is sometimes called the "brains" of the personal computer also. The rate at which the CPU runs system instructions is also referred to as its speed and it is measured in Hertz. The faster the processing unit is, the more quickly scripts and web apps will be executed, though the performance of the latter depends on other things also - the read/write speed of the hard disk drive, the amount of physical memory, the network connection, and many others. All current CPUs have several cores, that work together. Because of this, the overall performance and the workload a CPU can handle increase, because every single core can process various tasks independently and numerous cores can handle one task that cannot be processed by a single core.