There are a number of ways that you can paint with light. The most common is to take a sparkler (also known as fireworks' smaller, safer sibling) and wave it about when your camera is set to a long exposure. You can also use LED lights in order to capture some light painting. The latter obviously last longer, and they create a firmer line, which can be utilized in order to create some highly detailed patters. If you throw unique colors into the mix, the results can be truly astonishing.
The long exposure time set on the camera means that you will capture the movement of the lights as they travel about, creating long twirls of color across the image that represent the actual paths of the objects. Below are some of the best examples of light painting.
If you have any of your own, be sure to share them.