A lighthouse has a very strong lamp at the top. The idea is to project light from this lamp as strongly as possible for a great distance. To do this, the lamp has a parabolic reflector. This has the shape of a parabola rotated about its axis. When a the light source is placed at the common focus of all the parabolic sections having a common axis, the rays are projected out parallel to the axis. Unfortunately today, the romance of lighthouses is being replaced with the accuracy of GPS!
