What Platelets Do

Platelets are cells that have a really important job: They help stop bleeding. They're like little sandbags that travel around in your blood vessels, ready to stop at the site of a cut or injury and build a little dam to stop the flow of blood.

Most of the time, that's a good thing. Let's say you get a cut on your finger.

Platelets floating by grab onto the cut and then onto each other and start building their little dam. This dam, called a blood clot, is what keeps your finger from bleeding too much.