Blood Type (En español: Grupo sanguíneo) Say: blud type Every person has a blood type. There are four major types, each with a different chemical marker that's attached to a person's red blood cells. These markers determine if someone has type A blood, type B blood, type O blood, or type AB blood. Each blood type can also be positive (+) or negative (-), just to make things a little more complicated! It's important that doctors know which blood type you have if you're going to have surgery, just in case you need some extra blood. But in an emergency, anyone can safely receive O-negative blood, regardless of his or her blood type. Back to Articles Related Articles 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.