All arithmetical and logical operations in a computer/server configuration are addressed by its Central Processing Unit, or CPU. This hardware part is oftentimes called the "brains" of the computer system as well. The rate at which the CPU executes system instructions is typically referred to as its speed and it's measured in Hertz. The swifter the processing unit is, the faster scripts and web applications will be executed, although the general performance of the latter depends on other things also - the read/write speed of the hard drive, the amount of physical memory, the network connection, and so on. All current CPUs have a number of cores, which work together. Because of this, the efficiency and the workload a CPU can handle increase, as each core can process different tasks independently and numerous cores can handle 1 task that can't be processed by 1 core.