Used to store the internal components of your personal computer e.g., hard disk, CPU, motherboard, power supply. The case of a personal computer has quite a few purposes, one is to ground the computer, to protect it from outside elements, to house the power supply for the motherboard. There are various sizes of PC cases such as midi and super large, it is best to get the largest possible because this means you can fit a large motherboard into it. The advantage of this is plenty of expansion slots.