What Are the Major Components of a Computer?

Computers are indispensable to work, home management, and entertainment in modern life. Knowing their parts and how they work together can help in diagnosing problems. Though they all use the same components, a laptop combines these parts into one compact unit while a desktop separates them into separate hardware pieces.


The case is the main hardware component of the computer and contains several circuit boards that define how your computer operates. The CPU (Central Processing Unit) is the brain of the computer and processes information. RAM (Random Access Memory) holds temporary information that disappears when the computer is shut off.. A video card for handling displays, a sound card for managing sound, a power source, and a cooling fan are also in the case.

Hard drive

A hard drive is magnetic media that stores information permanently. It can exist inside the case or can be externally connected through ports. Though low-end laptops can have hard drives starting at 100MB (megabytes) in size, terabyte (TB) drives are becoming more common. The larger the capacity of the drive, the more information it can store.


CDs and DVDs are the primary means of distributing programs. Your computer must play these discs on drives in order to download the software. Though separate drives exist for each disc type, they are more often combined into one drive to save space. A CD/DVD drive can also store information on a disc in a process known as “burning.”


A monitor or screen displays information from the computer. Its size is typically expressed in inches as a diagonal measurement from one corner of the screen to the opposite. Common sizes for desktop monitors range from 17 to 23 inches. Old and bulky CRT monitors have been all but replaced by more compact flat screens.


You enter information into a computer primarily by typing on a keyboard, which contain not only keys for letters, numbers, and punctuation marks, but those for functions such as moving the cursor and deleting text. Though wireless keyboards, most of them are still attached to the computer. More advanced keyboards can also feature on/off switches, media controls, and lighted keys.


A mouse moves the cursor on the screen, and activates or manages program icons through the use of buttons. Traditional mice accomplish this by moving across a mouse pad while trackballs save space by rotating a ball at a fixed location.


Modems connect the computer to the internet through a phone line or high-speed cable. They may exist inside the case or as an external device. Several computers connecting to the same modem or to each other use a router, which may also be part of a modem.