Once again, I'll assume you live in this planet and in this timeline. I'll also assume you've heard to anyone of these:
Jimmy Page of Led Zeppelin
Joe Trohman of Fall Out Boy
Then you've definitely heard an electric guitar, and even if you've never heard any of these bands and musicians in your life, you've almost certainly heard an electric guitar nonetheless. It's present in your neighbor's garage, in the music shop downtown, and in videos on MTV. The electric guitar has been part of our daily lives for around 50 years.
To understand the history of the electric guitar, one most understand the "pickups"
Pickups are basically transducers, devices that convert one type of energy into another type of energy. Microphones and Speakers are transducers (in fact, they are the opposite of each other: one turns sonic energy into electric energy, and the other turns electric energy into audible sound).
Pickups consist of magnets wrapped in copper wire. When the magnetic strings of a certain electric instrument vibrate, they modulate the magnetic flux of the coil, creating an alternating voltage in the wire's coil. This signal is then amplified or recorded through a cable.
The first commercially succesful electric guitar was the Rickenbacker "Frying Pan", an electric Hawaiian, played as a lap-guitar. Les Paul began working with "The Log", and his guitar was introduced by Gibson in 1952. Leo Fender introduced his solid body guitar in 1950. Solid bodies have more sustain than hollow bodies, and had less feedback problems.