If there was an easy answer, this website would be very small.
Unschooling is creating and maintaining an atmosphere in which natural learning can flourish.Joyce Fetteroll doesn't like "natural learning," so I don't think it will be her favorite. Other people have favorite aspects. It's worth reading a dozen or thirty of them, and trying them out yourself. The beginning of the one above came when I was speaking in Arizona, and it wasn't being recorded, but Roxana Sorooshian was taking notes. She came up later and showed me something I had said, unscripted, that turned out to be the clearest, simplest definition up to that time. I put it in The Big Book of Unschooling. It was:
Unschooling is arranging for natural learning to take place.But in the next few years, it was carried around, turned over, examined, tried out, and polished. I think "creating and maintaining an atmosphere in which natural learning can flourish" is good.
You can read lots more at any of these pages:
Several definitions from a long-defunct other site