Nothing is at rest in this Universe as everything is moving – stars, planets, moons, earth and everything on earth's surface - matter and energy in the in the form of molecules, atoms and sub atomic particles such as electrons, protons, photons and quarks.
The pattern of motion can be best described in terms of vibrations and waves to understand the nature of light, sound and electromagnetic waves. Wavelength which is a measure of the distance between peaks of the disturbance influence how a wave interacts with matter such as transmission, absorption, reflection, diffraction and interference.
The interaction of electromagnetic waves with matter depends on the wavelength and they are grouped with distinctive names like radio waves, microwaves, infrared waves, visible light, ultraviolet, X-rays and gamma rays depending on the wave length. Even the different wavelengths of visible light interact differently giving us the perception of colour. The sky appears blue as the atmosphere scatters short wavelength light much more than long wavelength light.