An input device.
A microphone converts sound into an electrical signal. There are many types of microphone but they all work on the same principle.
Sound is basically rapidly changing air pressure and so a microphone contains a 'diaphragm' that moves back and forth as the sound waves hit it. This movement is detected by some electronics which produces an electrical signal. This signal is then fed into a sound card or audio amplifier.
Challenge see if you can find out one extra fact on this topic that we haven't already told you
Click on this link: Microphone