Simple Definition:

Electromagnetic induction is the creation of an electric current in a conductor [a material that allows electricity to flow through it] due to a changing magnetic field. When a conductor is exposed to a magnetic field that is either moving or changing, it causes the electrons in the conductor to move, generating an electric current. This process is used in many everyday devices, such as generators [machines that convert motion to electricity] and transformers [machines that convert one current to another], to produce and transmit electricity.

Very Simple Definition:

Electromagnetic induction is when electricity is made when a magnet moves next to a wire or a wire moves next to a magnet. This happens because the magnet’s movement or the changing magnetic field makes the electricity flow in the wire. It is used in things like generators [machines that convert motion to electricity] and transformers [machines that convert one current to another] to make and move electricity.