How Blood Types Were Discovered?

Blood types were discovered when scientists noticed how blood works differently in different people.

Imagine you're playing a game where everyone has to share toys. Some kids have red blocks and blue blocks; others only have red or only blue. When two kids try to share, sometimes the blocks fit together perfectly, like puzzle pieces, but other times they don’t match up at all.

In the 1900s, scientists were like the toy-sharing kids. They noticed that when they took blood from one person and gave it to another, sometimes the body welcomed it like a friend, but sometimes it reacted like it was being attacked by strangers.

Scientists started experimenting with blood. They mixed blood from different people and watched what happened. Sometimes the blood stayed calm, that meant it matched up well. Other times, it got all clumpy and angry, like when someone tries to drink a milkshake and it’s too thick.

By doing these experiments again and again, they found out that there are different kinds of blood, just like different kinds of toys. They named them A, B, AB, and O, kind of like naming your favorite toys!