Photons

When explaining light and spectrums, we use photons.

A photon is an elementary particle and a quantum of electromagnetic energy. Photons do not have a real size, and can not be split, only created or destroyed. Light sources will emit light in bits, and these bits are photons. Photons are "packets", and contain a certain little bit of energy. The more photons a light source reflects or sends back, the brighter the light will be. The energy of the photon depends on its wavelength.

Definitions
Photon elementary particle, light quantum of electromagnetic energy

Elementary particle simplest and smallest particles that make up everything in the universe

Quantum "how much" in latin, defined as smallest discrete amount of a unit or something