The visible light spectrum is the portion of the electromagnetic spectrum that we know best. It is the range of electromagnetic radiation that a typical human eye can detect, with wavelengths ranging from about 380 to 740 nanometers. In terms of frequency, this corresponds to a band in the vicinity of 430–770 THz.

Light travels in straight lines at approximately 300,000,000 meters per second. It travels in waves that can pass through a vacuum (empty space). They do not need a substance to travel through, like sound waves do through air or a solid medium. Light can travel through transparent substances like air, glass, and water. These substances transmit light with very little absorption.

Translucent or opaque materials, like lamp shades and sunglasses, transmit some light but are not completely clear. Some wavelengths or colors of light are absorbed and do not pass through to our eyes. The material acts as a...