When light hits an object, one of three things can happen to it.

Light can be reflected, where it bounces off at the same angle that you hit it at. A mirror is an object that bounces off most of the light that hits it and is the source of its reflective nature.

A quick experiment that you can do is to take a flashlight and point it directly at a mirror. If you did this right, you probably got blinded a bit. The light is bouncing straight back into your eyes. Now, move a bit to the left, but point your flashlight straight out from your body towards the point you were aiming at before. The light from your flashlight will appear to light up a place that is not the mirror you are pointing it at. As you keep moving to the left while aiming at the same point on the mirror, the spot reflecting back from the mirror should be moving away from you. That is because mirror is reflecting the light at the SAME angle you are hitting it at. So, the wider the angle that light hits a mirror, the farther away from its starting point it will end up.

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