Light painting, also known as light drawing or light graffiti, is a photographic technique in which exposures are usually made at night or in a darkened room by moving a hand-held light source or by moving the camera. In many cases the light source itself does not have to appear in the image.
The term light painting also encompasses images lit from outside the frame with hand-held light sources. The first known photographer to use this technique was Man Ray in his series "Space Writing" created in 1935. Photographer, Ellen Carey, discovered Man Ray's signature signed by penlight nearly 74 years after the pictures had been taken. For this theme, give us some dazzling works of art, created with light!
More info about light painting on Wiki.
If you have no idea where to start, here is a light painting guide.