Life on earth would be impossible without light. Plants use energy from the sun to grow and make food for all living things.
Light is a form of energy which travels in small, invisible waves.
Light moves faster than anything else in the universe. It can travel more than 186,000 miles per second. But light does not travel through all substances at the same speed. Like you, light moves more quickly through air than it does through water. When light slows down, it bends.