What are private sales of handguns?

Again i ran into this quest., b/c the politics book failed to define what exactly amounts to private sales of handguns?? i am guessing like criminals selling guns online or something??

I means the owner of a handgun does not have to have an FFl to sell his personal collection. He still can't sell to a minor or known felon. This practice is still in force here in Ohio. I am a collector and buy privates sales occasionally. the risk is if it turns out to be a stolen guns you can't get your kinkies back….