There are four types of computer:
1. Supercomputer - are the most powerful type of computer. These machines are special high-capacity computers used by very large organizations.
2. Mainframe computer - occupies specially wired air-conditioned rooms. Although not nearly as powerful as supercomputers, mainframe computers are capable of great processing speeds and data storage.
3. Minicomputer - also known as midrange computers, are refrigerator-sized machines. Medium-sized companies or departments of large companies typically use them for specific purpose.
4. Microcomputer - are the least powerful, yet the most widely used and fastest-growing type of computer.

Microcomputer is the most common type.

There are six types of Microcomputer.
1. Desktop computers
2. Media center
3. Notebook computers/Laptop computer
4. Tablet PC
5. Netbook
6. Handheld computer (PDAs/Smartphones)