The Central Processing Unit (CPU) is the brain of the computer. The CPU processes all data entered by the keyboard, mouse and programs and that data is then directed through a set of commands to provide the appropriate response. For example, when you type the letter 'U' the processor translates the binary code for that letter and send that information through the program and onto your screen. Of course this happens in Nanoseconds but for a single character of text, there is a great deal of information moving from one place to the other.
