Long exposure photographs are made when a photographer leaves the shutter of a camera open for a longer than usual time; most shutter speeds are fractions of a second up to a second. Long exposure images may be taken with the camera shutter open for a few seconds, or even hours. The resulting image is quite different, as if time were slowed down. It gives an entirely new perspective to otherwise commonplace and familiar images. Particularly interesting long exposure shots are often composed to include both stationary objects and moving objects, especially in dim light or even at night. Common long exposure shots involve night shots of cars moving, fireworks, or other moving light sources like fountains, or fire. Light sources often create interesting light trails.

Some photographers use specific techniques, like these solargraphs from Bob Fosbury (click on the marked regions for explanations of his technique). This site discusses specific techniques for composing long exposure shots, with examples. There are more example shots here and here. There's a good basic discussion here. For a detailed discussion of exactly how to compose and take long exposure photographs, see this careful step by step long exposure tutorial site from photographer Dan Heller.

Photo credit: Aaron Jacobs