All arithmetical and logical procedures in a computer/server configuration are handled by its Central Processing Unit, or CPU. This hardware component is occasionally called the "brains" of the computer system as well. The rate at which the CPU carries out system instructions is usually referred to as its speed and it's measured in Hertz. The quicker the processing unit is, the speedier scripts and web apps will be executed, even though the efficiency of the latter depends on other things too - the read/write speed of the hard drive, the amount of physical memory, the network connection, and many others. All modern CPUs have multiple cores, which work together. Therefore, the efficiency and the workload which a CPU can manage increase, because every single core can process various tasks independently and several cores can handle one task that can't be processed by a single core.