What Is a CPU
And What Your
Computer CPU Does?

Central Processing Unit, Computer CPU, is the component installed in your motherboard socket. The CPU executes and interprets programs, and processes data.

AMD Processor

Like a calculator It reads the information you give, interprets it, executes the equation, then writes back the result. This gives you the big picture.
CPU comes in 2 brands, AMD and Intel. Both build equally good CPUs, with their own features.
I think, Intel tend to be more stable and AMD faster for games. But it is just my 2 cents; nothing precise here, only a personnel observation.
Here some CPUs with their features from AMD and Intel:

• 32-bit AMD Athlon, Athlon XP with SSE2, SSE3
• 32-bit Intel Pentium 4, Pentium D with Hyper-Threading
• 32-bit Intel Pentium M with Low Power
• 32-bit Intel Dual with Dual-Core
• 64-bit AMD Athlon 64, Turion 64 with Dual-Core
• 64-bit Intel Dual Core 2 with Dual Core

For those who are seeking more advanced information you will find links throughout the content and at the bottom page as how to install CPU.

Computer CPU Forms

CPUs come in several forms, and each one has his reason to be that I discuss in more details in the CPU socket type page. For the introduction's purpose I will only give a general idea of the 2 most used forms as the LGA and PGA.
The Pin Grid Array (PGA). The PGA CPU has pins on its front to be fixed in the motherboard socket. As you can imagine, the socket grid has holes to receive the CPU pins.
The Land Grid Array (LGA). The LGA CPU does not have pins like the PGA and it is landed on a socket grid that contains pins. In some way, it is the opposite of the PGA form.

What Is The Computer CPU Speed And/Or CPU Clock Rate?

The CPU speed is the clock rate frequency in hertz ( circles per second) at which the CPU executes standard operations like doing equations, processing simple data and so on.
In the old days, computers had clock frequencies as low as 4.77 MHz (4,770,000 cycles/second), but nowdays the standard is around 3 GHz (three billion cycles/second).

For now on, CPU's fabricants are working on the CPU core to enhance the speed. As they are stuck with a frequency cap, building CPUs with a clock rate frequency over 3.6 GHz start to be a hard task. I guess it is due of circuits overheating too much.

The FSB Architecture And Motherboard Chipset

The Front Side Bus (FSB), is the data bus between the CPU and the motherboard's northbridge chip. The chipset (northbridge and southbridge) allow the communication among all buses (memory, PCI, AGP, PCIe).
Imagine the FSB as a booster for the CPU for managing programs faster. Before the FSB architecture, CPUs were just fine. But today's programs demand too much power from the CPU to be able to execute fast enough. Higher is the FSB, faster the CPU can execute.
Having a low FSB frequency, is like putting your CPU on standby, waiting for the information to come.

CPU Overclocking, Good Or Bad?

It is possible to boost your CPU's overall performances by setting the clock multiplier and FSB higher than it has been built for. From the motherboard's bios or from a software, this is achievable.
Why overclocking?
Overclocking can be interesting if you feel your computer is a bit slow. It may help the computer performances with a small overclocking.
In the other hand, overcloking may cause erratic behavior such as, regular errors from the operating system, premature failures or the CPU that overheats or die sooner than it should. In some case with a very high overcloking, the CPU may die under a week.
I strongly disapprove the idea of overclocking. Why taking risks if at the origin the CPU has been build for a certain power and not higher. Unless you plan to buy a new CPU do not overclock.