I’m sure you’ve seen them on a hospital related television show before. Triage tags are used by emergency responders in the field, during mass casualties. These tags help responders to quickly identify who needs care right away and who can wait. This is extremely important when there are more patients than responders.
Most places use some sort of paper tag like the one seen below.
But in the modern world we live in even the triage tag is getting its update. These triage lights come in four colors (red, amber, green and blue) and run off a user replaceable battery that has a shelf life of up to 5 years. The lights have a blinking function which helps responders distinguish between contaminated and non-contaminated patients during a HAZMAT situation as well.
You can learn more about the lights here.