The document discusses reflection and refraction of light. It defines reflection as light bouncing off a surface, maintaining the angle between the incident and reflected rays. Refraction is defined as the bending of light when passing from one medium to another, such as from air to glass, due to a change in speed. The key points are that the angle of incidence equals the angle of reflection for reflection, and light bends toward the normal when going from a less dense to more dense medium for refraction. Plane mirrors form virtual upright images that are laterally inverted.