Photographic umbrellas are constructed similar to a rain umbrella, but made with materials that control light. Most umbrellas are black on the outside with a reflective surface inside. Lighting units are mounted such that they are pointing into the umbrella. When triggered, the light bounces around inside of the umbrella then out toward the subject providing non-directional lighting. The lighting from a photographic umbrella is typically smooth and soft.
Umbrellas are quite common do to their low cost and great results. Many portrait photographers favor umbrellas to softboxes because of the round catchlight, or reflection they produce in the subjects eyes.
Umbrellas have been manufactured in many variations of size and color. Some are even designed to be convertible, having their black backing removed, which allows the light to pass through the inner layer of diffusion material. These umbrellas provide great flexibility and creative options.