=The ray of light which strikes the surface is called the incident ray. =The ray of light which leaves the surface is called the reflected ray. =A line perpendicular to the surface is imagined at the point of reflection. This line is called a normal. In this ontext the word normal means perpendicular. =The angle between the incident ray and the normal is called the angle of incidence, or the incident angle. =The angle between the reflected ray and the normal is called the angle of reflection, or the reflected angle.