Light travels as waves in the electromagnetic spectrum at different wavelengths. It travels fastest in a vacuum at 300,000 km/s and slower in other materials. Light interacts with objects by being absorbed, reflected, or transmitted. The wavelength of visible light is between 400-700 nm. Color is determined by the wavelengths of light reflected from an object. Monitors produce color using red, green and blue light while objects use pigments that absorb certain wavelengths. Reflection and refraction of light can be regular, diffuse, or involve total internal reflection as in fiber optics. Lasers produce coherent light of one wavelength.