An image is formed by reflection when two or more reflected rays of a point meet at a single point. The image is formed at the point of intersection of the reflected rays.
Characteristics of image formed by a plane mirror
Image formed by a plane mirror is virtual, erect, same size as of object and laterally inverted. Also, image distance(distance between image and mirror) equals the object distance(distance between object and mirror) for a plane mirror.
Lateral Inversion in Plane Mirrors
Lateral Inversion: In the mirror the right appears left and the left appears right. Note that only sides are interchanged; the image does not appear upside down. For example in the given figure ambulance is written opposite so as to be seen correctly in the mirror of the vehicle moving ahead.