Your blood contains many tiny cells called platelets. They help your blood clot, which means that if you get a cut, some of your platelets stick together to plug the hole in the blood vessel wall caused by the cut. Eventually, the clot dries out to form a scab to protect the healing skin underneath.
© 1995-2014 KidsHealth® All rights reserved. Images provided by iStock, Getty Images, Corbis, Veer, Science Photo Library, Science Source Images, Shutterstock, and Clipart.com