Faraday proposed in 1847 that light was a high-frequency electromagnetic vibration.
Just a word about polarization of light.
Light is a wave, but the waving
has two arms perpendicular to each other
and perpendicular to the direction of propagation.
A polarized light eliminates one of these arms,
so that the light waves in only one direction.
See also in The book of science:
Readings on wikipedia: