Which kind of blood are people able to donate?

There are four main blood types: A, B, AB, and O. People can only donate blood to someone who has the same blood type or a compatible blood type.

Compatible blood types:

* A+ can donate to A+ and AB+

* A- can donate to A+, A-, AB+ and AB-

* B+ can donate to B+ and AB+

* B- can donate to B+, B-, AB+ and AB-

* AB+ can donate to AB+

* AB- can donate to AB+, AB-

* O+ can donate to O+, A+, B+, AB+

* O- can donate to O+, O-, A+, A-, B+, B-, AB+, AB-

It's important to match the blood type of the donor with the blood type of the recipient to avoid any adverse reactions.