Light painting is a photography technique that uses light sources and a long shutter speed to capture traces of movement. The document discusses how the author experimented with shutter speeds between 1-5 seconds to light paint photos in a dark studio using fairy lights, torches, and glow sticks without flash. Shutter speeds of 1 second were too dark and 5 seconds too blurry, so speeds of 2-3 seconds produced the best lit, non-blurry photos.