The light penetrating our eyes, an incoming call on a mobile phone, or an X-ray at the dentist: all are different kinds of light, or electromagnetic radiation. This illustrated guide to the electromagnetic spectrum explores the nature of light wavelength by wavelength – radio waves, microwaves, infrared, visible light, ultraviolet, X-rays and gamma-rays – revealing the properties, characteristics and practical applications of each type of radiation with incisive explanations, diagrams and hundreds of full-colour photographs.