I didn't know until a few years ago when I was given the name of a doctor that was supposed to be so good that you would think the man walked on water.
So... I after several years of hearing about him (and also me complaining that he wasn't on my insurance) I googled him. He was a DO and the first thing I thought of was "What the bloody heck is a DO?" That was a few years ago. So that made me go research and now I know.