Burn, third-degree A burn is an injury that's caused by heat or fire. A third-degree burn is the most serious kind of burn. This kind of burn damages all of the layers of the skin and also the tissues underneath the skin. (Not the tissues you blow your nose in! We mean the stuff your body's made up of.) Back to Articles Related Articles Being Safe in the Kitchen Cooking and baking are lots of fun - as long as you stay safe. Read this article for safety tips before you head into the kitchen. Read More Word! Burn, First-Degree A first-degree burn is one that only hurts the top layer of skin. Read More Word! Burn, Second-Degree A second-degree burn is one that hurts the top two layers of skin. Read More Your Skin No matter how you think of it, your skin is very important. It covers and protects everything inside your body. Read More How to Be Safe When You're in the Sun It's fun to be outside on a hot, sunny day. But too much sun and heat can make you feel terrible. Find out how to stay safe in this article for kids. Read More Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor. © 1995-2021 KidsHealth®. All rights reserved. Images provided by The Nemours Foundation, iStock, Getty Images, Veer, Shutterstock, and Clipart.com.