A stump grinder is a machine with a heavy rotating cutter wheel that grinds the visible stump and the top of the root flare down to wood chips. It does not pull out the entire root system — those roots stay underground and decompose naturally over the next 5–10 years. For 90% of homeowners, this is exactly what you want: the stump is gone, the spot is usable, and you didn't pay for unnecessary excavation.