A mirror that has a reflective surface curved inwards, e.g. in the shape of a bowl or parabola. The surface of such a mirror reflects all the rays incident on it into a single spot called the focal point. It is used to concentrate light and has applications in, for example, reflecting telescopes or solar concentrating power plants. It can be used to create light beams, e.g. in car headlights, by placing a small light source in the focal point of a concave mirror.