All arithmetical and logical functions in a computer/server configuration are tackled by its Central Processing Unit, or CPU. This hardware element is typically called the "brains" of the computer system also. The rate at which the CPU runs system instructions is typically referred to as its speed and it's measured in Hertz. The quicker the processing unit is, the faster scripts and web apps shall be executed, though the general performance of the latter is determined by other things as well - the read/write speed of the hard disk drive, the amount of physical memory, the network connection, and many others. All modern CPUs have multiple cores, that work together. For that reason, the overall performance and the workload which a CPU can manage increase, since each and every core can process different tasks independently and numerous cores can handle a single task that can't be processed by a single core.