Clothing that lights up might sound like something out of a science-fiction movie, but electronic textiles (or e-textiles for short) — also called "wearable electronics" — are actually used in the real world for both decorative and practical purposes. For example, some T-shirts contain strings of lights that light up in response to sound (you can find them online by searching for "LED shirt"). Some police officers use traffic control gloves that flash with built-in red and green lights to give stop-and-go signals to traffic: