Light is a form of energy that is part of a much bigger family called the electromagnetic spectrum .
All matter is made from molecules that move because they have thermal energy . Molecules are made from charged particles and it is the movement of the charges that sets up changing electric fields. Now, a changing electric field induces a changing magnetic field in the adjacent space, and the changing magnetic field induces a changing electric field, and so on. Thus, an electromagnetic disturbance moves through the space from one place to another, even if the space is a vacuum. The disturbance acts as if it was a wave, transferring energy from A to B, with a range of wavelengths.