How Do The Pickups On An Electric Guitar Work?

An electric guitar pickup is a device which consists of a wire wrapped around a magnet. When any piece of metal like for instance the electric guitar moves about it the magnet's magnetic flux changes and this causes a voltage in the wire. The voltage and the string above it will oscillate in tandem. The pickup can thus translate the sound or in this case mechanical oscillation into voltage oscillation which can be easily transmitted to wires.
  
The pickup will act as a transducer and converts the vibrations which can then be amplified and if desired recorded. There are different kinds of pickups. Some types include magnetic pickups, piezoelectric pickups, Multi transducer pickups etc. There are active and passive pickups as well. A serious guitar player is always particular about the pickup used considering they can considerably alter the sound of the music.