All arithmetical and logical functions in a computer/server configuration are tackled by its Central Processing Unit, or CPU. This hardware element is sometimes called the "brains" of the PC also. The pace at which the CPU carries out system instructions is commonly referred to as its speed and it is measured in Hertz. The swifter the processing unit is, the faster scripts and web applications shall be executed, though the overall performance of the latter depends on other things too - the read/write speed of the hard disk drive, the amount of physical memory, the network connection, and so forth. All current CPUs have a number of cores, that work together. For that reason, the overall performance and the workload that a CPU can tackle increase, since each core can process several tasks independently and several cores can handle 1 task that cannot be processed by one core.