All arithmetical and logical operations within a computer/server configuration are addressed by its Central Processing Unit, or CPU. This hardware component is sometimes called the "brains" of the personal computer as well. The rate at which the CPU completes system instructions is usually referred to as its speed and it is measured in Hertz. The quicker the processing unit is, the quicker scripts and web apps shall be executed, though the performance of the latter is dependent upon other things too - the read/write speed of the hard drive, the amount of physical memory, the network connectivity, and many others. All modern CPUs have multiple cores, that work together. Therefore, the overall performance and the workload a CPU can handle increase, as every core can process various tasks independently and a number of cores can handle one task which cannot be processed by a single core.