light painting

Short definition from Wiktionary

Noun

1. 1
   The artistic technique of moving a light source to selectively illuminate parts of the subject or scene a camera is recording (at a slow shutter speed), or to shine directly into the camera and in this way sketch.
2. 2
   Camera painting, the artistic technique of moving a camera (while it records at a low shutter speed) such that light sources appear in multiple places or as streaks in the resulting photograph, the "painting".
3. 3
   A painting created using one of these techniques.
4. 4
   Used other than figuratively or idiomatically: see light, painting.