A central processing unit (CPU) or processor, is an electronic circuit that can execute computer programs.

Different CPU's

CPUs are broken into the behemoth companies Intel and AMD. Choosing from one or the other will in most cases decide your motherboard for most motherboards only support one or the other. There are Single Core, Duel Core, Triple Core, and Quad Core processors.

What one should i get?

Usually when deciding a CPU more cores the better the Processor is. When choosing from AMD or Intel go by reviews and benchmarks instead of name brand. Before buying your processor consider what the system is going to be used for.

Single Core:

If you are going to use your system for word-processing, browsing the web or other basic tasks, it may be sufficient for you to use a single core processor such as Intel Celeron or an AMD Athlon 64 processor.

Duel Core:

If the system is going to be used for spreadsheet, databases, graphics and playing some moderate video games then you should consider a duel core processor such as an Intel Core 2 Duo or an AMD Athlon 64 X2 processor.

Quad Core:

If the system is going to be used as an advanced workstation for doing work such as Video Editing, CAD, or playing the latest video games or other CPU intensive tasks then you will need a higher end quad-core or multi-core processor such as AMD Phenom X4, Intel Core 2 Quad or Intel i7.

CPU Checklist

1. Check to see if motherboard is Intel or AMD compatible.

2. Make sure CPU Socket on motherboard is the compatible with CPU type you are getting

3. In most cases more cores are better, but GHz is also important make sure if you are doing activities that don't require as much multi-tasking get a higher GHz processor then more cores.