Light is a kind of energy which helps us in seeing the world around us. Light travels in a straight line. When light falls on a shiny surface, most of it goes back in the direction from which it was coming. This phenomenon is called reflection of light. Plain mirror is the most common item which works on reflection of light. The image which we see in a plain mirror is a virtual image. A virtual image cannot be obtained on screen. The image in a plain mirror is laterally inverted and that is why your left hand looks like the right hand of your mirror image.