A CPU is the brain of a computer where most calculations take place. It is the most important element of a computers system. It is an hardware with in the computer that controls your instructions.
RAM stands for Random Access Memory. It is the most common type of memory/drive found in computers. Its job is to keep your data, every time you open a page on your computer, it gets downloaded from your hard drive into the RAM.
A motherboard is the biggest piece in a computer. All the small pieces are attached to it and the motherboard functions it. It is very important and you need to have on so your computer works.