Some computers are used to perform special stuff. They may be programmed to perform a task, let say for studying earthquake or for controlling some devices. However, the most common type of computers that you can see everywhere is called personal computers, used mainly for surfing the net, watching videos, doing admin task and more. Nowadays a lot of manufacturers are competing with each other, building the ever-smaller computers. Well, it’s the trend now, human like mini portable stuffs. Apple has been good at this and introduced Macbook air with revolutionary thin size, and now has also come up with the concept of Apple watch which is a wearable computer-like device
Big desktops are no longer in fashion as there are smaller desktops with all-in-one design is being widely used. Desktop computers are small enough to sit in your desktop, laptop are small and light enough to be operated on a person’s lap, notebook and large tablets are portable enough to be carried everywhere and PDAs (now obsolete), smartphones and small tablets are small enough to be held on the palm of your hand.
Minicomputers are more powerful and to be be used by more than one person at a time. For e.g, All cash machine in a store maybe connected to a microcomputer which stores all the financial and inventory data.
Mainframes computer are large powerful and expensive computers, which size of maybe a refrigerators. They are used mainly by government, fbi, banks, airlines etc.
On the other hand, super computers are the fastest and most powerful computers, mainly designed to tackle complicated problems that required a lot of computer time and speed. They may be used for research purposes.
With recent advances in hardware, the boundaries between these different types of computers is blurring. Even the desktop computers that are used at home have multiple processors (Intel Pentium Quad-core processor)