What are the components of a computer?

The components that must need so that a compter could boot to BIOS are:
1. Motherboard
2. CPU
3. RAM
4. Video Adapter
5. Power Supply Unit
6. Keyboard
7. Monitor

The components that a computer must add so that it can install OS, and could boot to the OS successfully are:
8. HARDDISK
9. ROM Drive

but there are still something added to normal computers these days:
10. Audio Adapter
11. Lan Card
12. Case
13. Speaker
14. Mouse

There are still many thing that could add, and they are optional, for example, RAID Card, SCSI card, TV-card, etc. I will not list those stuff.