All arithmetical and logical operations inside a computer/server configuration are addressed by its Central Processing Unit, or CPU. This hardware element is typically called the "brains" of the computer as well. The pace at which the CPU executes system instructions is generally referred to as its speed and it is measured in Hertz. The swifter the processing unit is, the more quickly scripts and web apps will be executed, even though the general 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 modern CPUs have multiple cores, that work together. Therefore, the functionality and the workload which a CPU can take care of increase, because each core can process a number of tasks independently and numerous cores can handle a single task which cannot be processed by 1 core.