Hardware

What is hardware again?
Hardware of a computer system can be divided into categories. What are these (four, or recently five) categories?
Name three input devices
Name three output devices
In which category does a digital camera belong (if you assume it belongs to a computer system)?
In which category does a touchscreen belong?
What is the difference between primary storage (memory) and secondary storage?
In which category does primary storage belong?
Name three (secondary) storage devices.
Is there a secondary storage device every computer has?
What different categories of computers do exist? What are the differences?