Hey kiddo, have you ever heard of hazardous materials? They are things that can be dangerous if we touch them, breathe them in or eat them. This is why people who work with hazardous materials need to be careful and wear special clothes to stay safe.
To help people identify these types of materials, the government created something called the Hazardous Materials Identification System (HMIS).
It works kind of like a coloring book! The colors are used to show how dangerous a material might be. For example, blue might mean the material is not very dangerous, yellow might mean it's a little bit dangerous, orange might mean it's more dangerous, and red means it's the most dangerous of all.
The system also uses numbers to show how serious the danger is. Zero means it's not dangerous at all, while four means it's extremely dangerous.
Combining the colors and numbers lets people who work with hazardous materials know exactly what they are dealing with and how careful they need to be.
In short, the Hazardous Materials Identification System is a way to help people stay safe when working with dangerous materials, by using colors and numbers to show how serious the danger is.