What does the term "Overclocking" mean?

Merriam-Webster Online Dictionary:
clocking: 2: to register on a mechanical recording device
over: 2: beyond some quantity, limit, or norm often by a specified amount or to a specified degree

A BRIEF description of overclocking a processor would be to run the processor above what it was intended to be run at.  That is that your computer runs at a certain speed, (you've probably heard of a computer running at so many megahertz; pronounced 'me-g&-"h&rts'; abbreviated MHz; megahertz refers to what speed the CPU (Central Processing Unit, also called processor, the "brain" of the computer) performs it's calculations, some CPU's even perform at gigahertz levels).  Anyway, a CPU that is "clocked" to a higher MHz number runs faster than one that is "clocked" to run at a smaller number. If you "clock" the CPU (more on this later) to run at a speed OVER what the processor was specified to run at when it was sold (by whoever fabricated the chip), then you are "overclocking" the processor.

Overclocking a processor means that the chip that the company said was okay to run at 150MHz, your now running at 200MHz.  Think of this as driving a car at 100 Mph that the car company said could safely run at 70 Mph.  Sure the car can hit 100 Mph, and you can probably even drive it for a few miles no problems and you'll get to your destination a few minutes faster., but let's say your car isn't very aerodynamic and starts to shake and rattle at 100 Mph, you'll need to do something to change that.  Also if you make a small over correction at 100 Mph your likely to flip the vehicle as opposed to what would happen at 70 Mph.  Additionally, driving a car at 100 Mph will probably wear out the engine faster than driving it at 70 Mph.  In computer terms this mainly means that running a processor hotter than what the company says is safe will shorten the life and make your computer crash more often, but will also get you where your going faster.

How does the processor know what speed it's clocked to run at?  Well on Pentium, Pentium II, AMD K6-2, and a few others, there are settings on the "motherboard" (the board the CPU is connected to) that are controlled by "jumpers".  Just think as jumpers as on/off switches for the motherboard to know what to do whenever you turn it on.  These jumpers tell the motherboard to clock the CPU at a certain Clock Frequency, and then to multiply that clock frequency by a multiplier, which is the motherboards "bus" speed.  (To put it simply the bus speed is the speed at which data is moved from one component to another on the motherboard.  If another add-in card, or any other component on your motherboard doesn't like the new bus speed it will crash, so sometimes limitations in overclocking don't always have to do with the processor, but back to our story)

Next: A closer look at jumpers.