"The mirror tests the reflection of light and the thoughtlessness of men".
It is a stigmatic optical system, since it always relates an object point with a point image. It also relates a real object with a virtual image, upright and of the same size of the object. There is an inversion of the image relative to the axis parallel to the mirror, but there is no reversal from top to bottom (see figure below). We call this type of image specular or regular.