The key components inside a typical desktop computer's system unit - highlighting the RAM, hard disk and CPU

1. System Unit
RAM (Random Access Memory)
- Where your programs and data
reside while you are using them
on your computer
The computer's hard disk
- where all your programs
and data are kept when
you aren't actually using
them
The CPU processor
- the brains of the
computer where all the
thinking and action is
going on