While we experience reality from one moment to the next, a camera is capable of capturing different expanses of time, together in a single image. A long exposure lets us stretch out our shutter speed for all kinds of abstract effects, and one of the most eye-catching is light painting.
By moving a light source such as a coloured torch around a scene during an exposure of several seconds, you can create stunning trails of light. To make light-painted portraits you need to shoot in a dark room (it needn't be pitch black), ask your subject to stay as still as possible, and set up your camera on a tripod. The right exposure settings will depend on the strength of the torches and any ambient light, but a good place to start is in Manual (M) mode with shutter speed at 13 seconds, aperture f/16 and ISO100. Press the shutter then start waving your torch or other light sources around your subject in smooth, flowing lines to paint with light. Try painting both in front of and behind your subject to add depth to the effect, and try shining your torch towards their face to illuminate that as well – remember to do this from the side so you're not captured in the final image.