Overclocking is not for every one. Successful overclocking will require some technical knowledge and a great deal of homework and planning. Overclocking a processor may void the warranty. Do it at your own risk.
Clock speed is one of the main factors that determine the computing power of a computer.
It is measured in MHz. The higher the number the higher the speed. Here is an analogy that will help you understand the concept. Of course, you want to run at higher speeds only at favorable conditions. The above analogy suggests that the clock speeds of a microprocessor may be arbitrary.