Headphones are electronic audio devices that people wear over their ears. They let people hear sounds on a walkman, MP3 player, mobile phone or computer. Headphones come in many different sizes from big to small. They are also known as earphones, stereophones, headsets or even 'cans'. Earbuds are inserted into the ear. Headphones typically uses small plug for connection. Some use a Bluetooth connection so they don't have the cord in the way.