Main Components of a Computer System

By Jack S. Waverly

The main components of a computer system are often taken for granted. We tend to think of a computer as one big collection of pieces acting as a whole. However, each component has a unique function and is much more useful as a part of the entire unit than operating on its own. Here are the main components of a computer system.


The most important component of a computer system is the CPU, or central processing unit, which consists of the Motherboard, hard drive, and connector cables.

Operating Systems

The Operating System runs the software on your computer, provides security and tracks other programs to ensure compatibility. Examples include Microsoft Windows, Linux or Apple's Macintosh.

The Monitor

The next main component is the monitor, or display screen. This screen also helps deliver warnings or messages when there is a problem with the CPU or Operating System.


The keyboard allows you to input commands and/or communicate with others on the Internet.


Using a mouse, you can interact with the Operating System or any variety of programs or software.

Hard Drive

Hard drives, where most information is stored, include the internal drives ("C" and "D") as well as the CD/DVD drives. They also allow access to the Operating System and other programs. Other hard drives include pen drives and zip drives.