All objects radiate energy and heat. Even your own body. Radiation leaves an object in the form of waves. Radiation uses electromagnetic waves such as ultraviolet, visible, infrared, and microwaves. Radiation coming from hotter objects is more intense than that coming from cooler objects.

An example is the radiation from a camp fire. If you held your hand out in front of you, what would you feel? Slowly your hand would begin to warm up as it absorbs the radiation coming from the fire. The infrared waves, or heat rays leave the hot fire, and radiate out towards your hands.