The processor (also called central processing unit, or CPU) is the part of the computer that actually works with the data and runs the programs.  Some computers have more than one processor and are thus called “multiprocessor”. This is distinct from multitasking. Advertisers often use megahertz numbers as a means of showing a processor’s speed. This is only a measurement of how fast it can operate (1 MHz = 1,000,000 clock cycles per second, it can roughly do 1,000,000 things per second). The CPU controls all other devices connected to the system.