We can see because light is

Light is energy that travels in a ray which is a narrow beam of light. We can see things because light bounces off things and goes into our eyes. You can also see things that give off their own light.

Light comes from many different sources which is the place where something begins or comes from. The largest light source is the sun and without it, Earth would be cold and dark. Stars make light too. So do things like lightbulbs, candles, computers, and TVs.