Remember that light can be used to mean visible lightbut can also be used to refer to other areas of the electromagnetism spectrum invisible to the human eye.
Each band of wavelengths represents a different form of radiant energy with distinct properties.
The idea of bands of wavelengths is adopted for convenience sake and is a widely understood convention. The entire electromagnetic spectrum is, in practice, composed of a smooth and continuous range of wavelengths (frequencies, energies).
Radio waves, at the end of the electromagnetic spectrum with the longest wavelengths and the least energy, can penetrate the Earth’s atmosphere and reach the ground but are invisible to human eyes.
Microwaves have shorter wavelengths than radio waves, can penetrate the Earth’s atmosphere and reach the ground but are invisible to human eyes.
Longer microwaves (waves with similar lengths to radio waves) pass through the Earth’s atmosphere more easily than the shorter wavelengths nearer the visible parts of spectrum.
Infra-red is the band closest to visible light but has longer wavelengths. Infra-red radiation can penetrate Earth’s atmosphere but is absorbed by water and carbon dioxide. Infra-red light doesn’t register as a colour to the human eye.
The human eye responds more strongly to some bands of visible light between red and violet than others.
Ultra-violet light contains shorter wavelengths than visible light, can penetrate Earth’s atmosphere but is absorbed by ozone. Ultra-violet light doesn’t register as a colour to the human eye.
Radio, microwaves, infra-red, ultra-violet are all types of non-ionizing radiation, meaning they don’t have enough energy to knock electrons off atoms. Some cause more damage to living cells than others.
The Earth’s atmosphere is opaque to both X-rays or gamma-rays from the ionosphere downwards.
X-rays and gamma-rays are both forms of ionising radiation. This means that they are able to remove electrons from atoms to create ions. Ionising radiation can damage living cells.