The animation shows you a ray of light hitting a plane mirror. A line drawn at right angles to the mirror where the light hits it is called the NORMAL to the surface at that point. The angle between the incoming light ray and the normal is called the angle of incidence (i) and the angle between the outgoing light ray and the normal is called the angle of reflection (r).
Laws of reflection
1 The angle of incidence is equal to the angle of reflection.
2 The incident ray, the reflected ray and the normal all lie in the same plane.