All arithmetical and logical operations inside a computer/server configuration are tackled by its Central Processing Unit, or CPU. This hardware component is sometimes called the "brains" of the personal computer as well. The pace at which the CPU executes system instructions is typically referred to as its speed and it's measured in Hertz. The quicker the processing unit is, the speedier scripts and web programs will be executed, though the efficiency of the latter depends on other things as well - the read/write speed of the hard drive, the amount of physical memory, the network connection, etc. All modern CPUs have multiple cores, which work together. As a result, the overall performance and the workload that a CPU can manage increase, because every core can process various tasks independently and a number of cores can handle 1 task which cannot be processed by a single core.