Electric guitars have pickups (a type of inbuilt microphone) and need to be played into an amplifier (amp) to be heard. There are two basic types of pickups which produce different types of sounds.
The classic Fender Guitars such as the Stratocaster and the Telecaster contain single coil pickups which produce a clear, crisp sound which is excellent for rhythm playing. Both guitars are also capable of producing biting trebly lead sounds. The most popular Gibson solid body Les Paul, and hollow body models such as the 335 contain double coil pickups. These produce a fatter, more chunky sound than single coil pickups. Many more recent guitars such as the solid body electric shown above contain a combination of single and double coil pickups.