The central processing unit is where programs go through mathematical functions to do their work. The motherboard has a place to install the CPU, RAM and wires leading to the hard drive, floppy drive, CD-ROM drivers and others.
Cards plug into the motherboard.
The performance of video cards varies greatly, with gamers preferring as much memory as 64 megabytes and office computers getting by on as little as 4 megabytes. A card that translates data from the computer into signals that can be sent over telephone lines. Compact discs are media for data storage. You can play your music CDs in a computer, but you can't play computer CDs, even those with sound files, on your music player. A CD-ROM player can read information off a CD, but it cannot write it onto a disk.