what are documentation fees on a used car

They are fees that dealers charge to make extra money. I rarely pay them. When I purchased our used CPO 2014 Lincoln MKZ the dealership told me the fees were $299.00. I told them that amount was ridiculous and I wasn't paying it. They told me I had to pay it. I said "no I don't" and got up to leave. They then abruptly took another $299 off of our deal. I would have walked out the door and went somewhere else had I not been credited the $299.