If you wanted to store some files you would choose the hard drive to do that.
Hard drives store storage and data. they process it as well, like it turns a file to an application and stores it inside of the hard drive.
Input and output devices
A device that sends data into the computer
Devices that the computer sends signals to
The CPU is measured in GHz
Most Computers have between 2 GHz to 3 GHz but if you've got a gaming pc or a more powerful computer then thats when it starts to get into 4 GHz
Its how many times the computer processes data in one second.
RAM is the speed ot the computer instead of GHz being the brain
IT stands for random access memory