Keyboard: to enter text. A keyboard can be physically or wirelessly connected to the computer. Wireless keyboards have become popular for their increased user freedom. However, wireless keyboards need batteries to work.

   External Ports: to interface with other devices. These may include Ethernet, Serial RS232, Firewire and USB ports.

   Jacks: for audio and speaker output. This may include microphone, speaker and stereo headphone jacks.

   Processor: to interpret computer program and process data. The two most popular processors are made by Intel and AMD. The faster the processor the better the performance. Processors can be single, duo, or quad core. High-end desktop computers are based on duo and quad core processors.

   Memory: to store and retrieve data. There are four types of memory used: system memory, hard disk, CD/DVD, and floppy disks. Hard drives can be internal or external. CD/DVD drives can be read-only or read/write capable. Floppy drives are becoming outdated.

   Software: to support different applications. Most desktop computers require an Operating System (Microsoft Windows OS). To be functional, most desktop computers require at a minimum email (Outlook), Word processing (Word), Spreadsheet (Excel), and an Internet Browser. Security software is also needed to keep viruses and spyware off the computer system.

Notebook or laptop computers are small and lightweight enough to be carried around with the user. They run on battery power, but can also be plugged into a wall outlet. They typically have a built-in LCD display that folds down to protect the display when the computer is carried around. They also feature a built-in keyboard and some kind of built-in pointing device such as a touch pad.

Notebooks are capable of the same tasks as Desktop PCs. While some Laptops are less powerful than typical desktop machines, this is not true in all cases. Laptops, however, cost more than desktop units of equivalent processing power because the smaller components needed to build laptops are more expensive.

Notebooks feature similar components as the Desktop PCs but more tightly integrated and in a different form factor.

A tablet PC is a notebook- or slate-shaped mobile computer. Its touch screen or digitizing tablet technology allows the user to operate the computer with a stylus or digital pen, or a fingertip, instead of a keyboard or mouse.

Tablet computers feature the following:

   Display: typically 8.4"-14.1" LCD screen. Most tablet screens are touch-sensitive and respond to tapping, drawing or writing with a stylus.

   Stylus: to move around the screen. It enables users to scroll, highlight, and select menu options. A stylus is a pointing and drawing input device shaped like a pen.

   Soft Keyboard: to enter text. A soft keyboard is sometimes called an on-screen keyboard or software keyboard. It replaces the hardware keyboard with an on-screen charater image map. With a soft keyboard, text is entered by tapping keys on the keyboard display, usually with a stylus.

   External Ports: to interface with other devices. These may include IrDA (Serial Infrared), Fast Infrared, Serial RS232, and USB ports.

   Wireless Connectivity: such as Bluetooth®, WLAN 802.11b or 802.11g.

   Software: to support tablet applications. Most tablet pcs run on Windows Mobile Operating System Edition. There are other operating systems in use on devices marketed as tablets.

A workstation is a powerful, high-end personal computer. They contain one or more microprocessors. Workstations are intended primarily to be used by one person at a time, although they can usually also be accessed remotely by other users when necessary. They may be used for applications requiring more power than a typical PC such rendering complex graphics, or performing intensive scientific calculations.

Workstations are often optimized for displaying and manipulating complex data such as 3D mechanical design, engineering simulation results, and mathematical computations. Consoles usually consist of a high resolution display, a keyboard and a mouse at a minimum, but often support multiple displays.

Workstations feature similar components as the Desktop PCs but with more processing power, memory capacity and multitasking ability.

A Server is a computer system that provides services to other computing systems, called clients, over a computer network. The typical server is a computer system that operates continuously and waits for requests for services from other computers on the network.

Servers supply files to client computers over a network. This class of powerful computers can also be used to handle the processing for many users simultaneously who are connected in a network system.

Servers often run operating systems that are designed specifically for use in servers. They also run special applications that are designed specifically to carry out server tasks.

Servers usually require large amounts of disk space. A Server can be accessed remotely through an ethernet connection or a serial port and usually does not require a display, a keyboard, a mouse, or graphics cards.