Computers
There are a lot of terms used to describe computers. Most of these words simply the size, expected use or capability of the computer. While the term computer can apply to virtually any device that has a microprocessor in it, most people think of a computer as a device that receives input from the user through a mouse or keyboard, processes it in some fashion and displays the result on a screen.
There are different types of computers
1: Desktop
A PC that is not designed for portability is a
desktop computer. The expectation with desktop systems are that you will set
the computer up in a permanent location. Most desktops offer more power, storage and
versatility for less cost than their portable brethren. 
2: Laptop
Also called notebooks, laptops are portable computers that integrate the display, keyboard, a pointing device or trackball, processor, memory and hard drive all in a battery-operated package slightly larger than an average hardcover book. Easy to portable
3: Netbook
Netbooks are ultra-portable computers that are even smaller than traditional laptops.Netbooks are desingned to use internet only.Netbooks are small in size . However, netbooks' internal components are less powerful than those in regular laptops.
4: PDA
Personal Digital Assistants (PDAs) are tightly integrated computers that often use flash memory instead of a hard drive for storage. These computers usually do not have keyboards but rely on touchscreen technology for user input. PDAs are typically smaller than a paperback novel, very lightweight with a reasonable battery life. A slightly larger and heavier version of the PDA is the handheld computer.5: Workstation
Another type of computer is a workstation. A workstation is simply a desktop computer that has a more powerful processor, additional memory and enhanced capabilities for performing a special group of task, such as 3D Graphics or game development.
6: Server
A computer that has been optimized to provide services to other computers over a network. Servers usually have powerful processors, lots of memory and large hard drives. The servers have two or more processors or harddrives if one fails ,the other harddisk or processor starts working
7: Supercomputer
This type of computer usually costs hundreds of thousands or even millions of dollars. Although some supercomputers are single computer systems, most are composed of multiple high performance computers working in parallel as a single system. The best known supercomputers are built by Cray Supercomputers.
