All arithmetical and logical procedures in a computer/server configuration are addressed by its Central Processing Unit, or CPU. This hardware part is typically called the "brains" of the computer also. The pace at which the CPU completes system instructions is typically referred to as its speed and it's measured in Hertz. The faster the processing unit is, the quicker scripts and web programs shall be executed, although the performance of the latter depends on other things as well - the read/write speed of the hard disk, the amount of physical memory, the network connectivity, etc. All new CPUs have a number of cores, which work together. As a result, the functionality and the workload a CPU can manage increase, since every single core can process a number of tasks separately and several cores can handle a single task that can't be processed by a single core.