by Greg Schwartz

Created on: July 30, 2009   Last Updated: December 05, 2010

Sure, we all use computers every day, but does anyone really know how they work?  Opening up a computer's case reveals a whole bunch of electronic circuitry that can look pretty confusing.  Let's break it down and see just how a computer works.

The CPU (central processing unit, also called the microchip or processor) is like a computer's brain.  It performs most of the calculations and works very fast.  The CPU is mounted on the motherboard, the main circuit board in a computer.  Every component inside a computer (and every external device, too, such as speakers or the mouse) connects to the motherboard.

Another main component is the hard drive (also called the HDD - hard disk drive).  The hard drive is the computer's long-term memory - except for the system clock and a few key settings, every piece of data stored on your computer is located on the hard drive.  Your hard drive is the reason you can set a picture of your dog as your desktop wallpaper, turn the computer off, and then turn it back on and see your dog's big drooling face staring back at you.  The hard drive is responsible for permanent data storage.

If a hard drive is the computer's long-term memory, RAM is its short-term memory.  RAM (Random Access Memory) is dynamic memory where your system stores open programs that it's currently using, such as Internet Explorer, and also where it keeps information that needs to be accessed quickly, or information that is constantly changing.  Your computer can access RAM much more quickly than it can access your hard drive.  If your computer is slow, adding more RAM can often speed it up.

Now that you've got this nifty machine with a brain and lots of memory, how do you interact with it?  How does it interact with you, or with other computers?  This is where input/output devices come into play.

An input device is anything that allows you to send data to your computer (in other words, communicate with it).  Input devices can be mice, keyboards, joysticks, even microphones.

An output device is anything your computer can use to export data, either to you (the user) or across a network or to another device.  Some common output devices include monitors, speakers, headphones, and printers.

Your computer can also send and receive data to and from other computers, via network cables and phone lines.  Modems and NICs (network interface cards) allow computers to communicate across networks

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