The two main artificial light sources are flash (off-camera or not) and steady-state lighting (i.e. light 'bulbs'). The latter includes studio lighting and also regular room lighting, or even outdoor lighting like street lamps or floodlights. In a sub-category of its own is on-camera steady-state lighting such as a ring light.

Reflectors and diffusers are not light sources, rather they are a means of redirecting or modifying the light from a source.

Umbrellas can be used as both a diffuser and a reflector, depending on what material they are and how they are positioned - a translucent material with the 'point' of the umbrella towards the model is a diffuser, whereas a reflective material with the inside of the umbrella towards the model is a reflector. Umbrellas are not used exclusively with steady lighting - they are often used with flash as well.

There are other kinds of reflectors and diffusers used in the studio, such as beauty dishes and softboxes.

Modifying the light is not the exclusive preserve of the studio, however. Disc reflectors and diffusers are actually more often used with sunlight rather than artificial light. Often the most dramatic and aesthetically pleasing shots are taken into the light. This causes exposure difficulties, however, as it means the front of the subject is in shadow. A simple reflector held in front of the subject bounces the light onto them, solving the problem. This can be a 'proper' photographic reflector or something as simple as a piece of white card.

Likewise, strong overhead sunlight can often cause exposure problems, with areas of intense brightness and deep shadow. A diffuser held between the sun and the subject softens the light (rather like a cloud) and creates better conditions for photographing them.