What is System Unit?

System Unit:

"The electronic components of computers and all the mobile devices which are closed in a case is called System Unit."

But it is notable thing that under this case all the electronic components which are used to process data.

Electronic components of a PC include all the motherboard in which processor,memory, chips, adapter cards(Video card, sound card), power-supply etc are present.

Common examples:

System Units: CPU, Laptop, Tablet PC, i phones, digital cameras, PDA,

Not system unit: keyboards, mouses, speakers, printers, scanners, USB flash, Monitors, LCDs,