A mirror forms an image such that its left side is object’s right side and its right side is object’s left side. This phenomenon of change in object and image sides is known as lateral inversion.

For example, the word AMBULANCE is painted left-right inverted on the ambulance so that when the driver of a vehicle in front looks into his rear-view mirror, he can make out the word AMBULANCE quickly and give way. As shown in the figure below.