Flat-Panel Displays
Flat oanel screens are used mainly with portable computers,such as notebooks and laptops,but are now also being used in the latests televisions,desktop screen,video games and cellular phones.These screens consist of two plates of glass with a substance in between them that creates the image on the screen.The different types of flat screens are:

1.Liquid Crystal Display(LCD)
2.Electroluminescent(EL)
3.Gas-Plasma

Output of Sound
Normal music system speakers are used to output sound.The quality of Sound depends on the type of system you use,the size of the speakers and the computer's audio card.The audio card is a circuit board in the computer that processes sound,similar to video graphics cards.

Video graphics card
A video graphics card,also called a display adapter,is a circuit board that determines the resolution,number of colors,and speed with whicj image appears on the screen.

Hard Copy Output Devices
Hardcopy out is permanent output and refers to output printed onto paper.
Printers can be divided into two broad categories.

1.Impact printers
2.Non-Impact printers

You'll have to do your own research on printers because I did my own research.