Question: what are the main parts inside a computer?
Answer: Motherboard. The motherboard is an important computer component because it's what everything else connects to! ... 
Power Supply. True to its name, the power supply powers all other components of the machine. ... 
Central Processing Unit (CPU) ... 
Random-access Memory (RAM) ... 
Hard Disk Drive / Solid State Drive. ... 
Video Card. ... 
Optical Drives.