1.Mobile Computing Device A class of very small, micro-processor based hand carried device such as a tablet computer such as the IPad and Android devices or Smartphones such as the IPhone and Windows Mobile devices. In addition to its microprocessor, a mobile computing device has a tiny keyboard, touchpad or touch screen for entering data, a small high resolution screen for displaying information, and a storage device such as an SD Memory Card for saving data.
2. Pc or personal computer A small micro-processor based computer. In addition to one or more microprocessors, a personal computer has keyboard for entering data, a monitor for displaying information, and a storage device for saving data. Some PCs are mobile and very small so they can be carried.
3. workstation A more powerful, single-user computer. A workstation is similar to a PC, but it has more powerful microprocessor (s), faster and larger data storage and higher-quality graphics. Usually used for some special application such as application development or computer graphics
4. Server A multi-user computer system designed to support hundreds of users simultaneously. A server can have many processors, some more than 32.
5. Mainframe A very powerful multi-user computer capable of supporting many thousands of users and millions of transactions simultaneously.
6. Supercomputer An extremely fast computer that computer that can perform hundreds of billions of instructions per second sometimes using a parallel processing architecture with hundreds or thousands of processors.