Radiation is defined as an emission of energy represented through electromagnetic waves or as moving subatomic particles. Radiation is the reason we are warmed by a fire. The heat radiates off the fire in the form of energy so that we are warmed by that energy. The heat from the sun is also a form of radiation that emits heat and light over the entire Earth.
There are also many other forms of radiation including the microwaves your microwave oven emit when preparing microwaved food. X-Rays, radio waves and ultrasounds are other examples of radiation. Radiation can be very helpful in some situations but it can also be dangerous and you must take caution.
