Sometimes referred to as earphones, headphones are a hardware output device that either plug into a computer line out or speakers. Headphones allow you to listen to audio or watch a movie without disturbing people around you. The picture is an example of a USB headset from Logitech, which also include a microphone (an input device), a popular solution for computer gaming.
If you have speakers connected to your computer, connecting headphones to the line out or headphones connection will result in sound only being output to the headphones. To have the sound output for headphones and speakers, you will need to use USB headphones.
The first pair of audio headphones were invented by Nathaniel Baldwin in 1910. The U.S. Navy ordered 100 pairs them because they recognized the potential advantages, despite many people being skeptical about their usefulness.
Headphones come in several shapes and styles. The traditional style looks similar to those shown above. They utilize styrofoam or another soft fabric around the earpieces to provide a comfortable fit around your ear, as well as a plastic or light metal band between each earpiece.
The most basic type of headphones, earbuds, are small and fit inside your ear. They are usually shaped in a specific way to be as comfortable as possible. Some earbuds come with several sets of different rubber inserts. Depending on the size of the user's ears, they can choose the size of rubber insert that best fits their ear canal. The picture to the right shows an example set of earbuds.