There is a bump on my wrist that is hard and hurts. it isn't on my other wrist either. would you know what it is?

Possible cyst : To give you a final answer it would be good to take a look at it but one common occurrence that presents as lump in the wrist is a ganglion cyst which is a protuberance that grows from the tissues that cover your wrist bones. This is the possibility in your case. Anyway, get checked and make sure you get the appropriate diagnosis.

Ganglion cyst?: It is probably a ganglion cyst. A ganglion cyst, also known as ganglia, is a fluid-filled mass that can occur at any joint, but it most commonly found on the thumb and palm side of the wrist.