So far I've learned:

The 3 main classes of computers:
1- PCs
2- Workstation
3- Mainframe

In computer organization, the 5 main components:
1- Input devices (ex: mouse, scanner etc.)
2- Output devices (ex: printer, speaker etc.)
3- Processor
4- Main memory
5- Secondary memory

Did you know? 1 byte = 8 bits.

The processor can typically:
1- add
2- subtract
3- multiply
4- divide
5- move data from location to location