Scab

As soon as you scrape or break the skin anywhere on your body, special blood cells called platelets (say: PLAYT-lits) spring into action. Platelets stick together like glue to make a clot. A clot is like a bandage over your cut that keeps more blood and other fluids from flowing out. The clot also has other blood cells and thread-like stuff called fibrin (say: FY-bren) to help hold the clot together.

As the clot gets hard and dries out, it is called a scab. Don't pick that scab — it will take longer to heal and you may even get a scar.