All arithmetical and logical functions in a computer/server configuration are addressed by its Central Processing Unit, or CPU. This hardware component is typically called the "brains" of the computer as well. The rate at which the CPU completes system instructions is generally referred to as its speed which is measured in Hertz. The faster the processing unit is, the quicker scripts and web apps will be executed, though the performance of the latter is dependent upon other things also - the read/write speed of the hard disk, the amount of physical memory, the network connectivity, and so on. All modern CPUs have multiple cores, that work together. Subsequently, the functionality and the workload which a CPU can take care of increase, since each and every core can process different tasks individually and a number of cores can handle a single task that cannot be processed by one core.