Tino Best was famously stumped against England at Lord's in 2004
If a batsman comes down the wicket to smash the ball, there's a chance they will be stumped by the wicketkeeper.
A stumping happens when the keeper collects the ball and knocks off the bails before the batter gets their bat or any part of their body grounded behind the batting crease.
Touching the batting crease with the bat or heel of the foot isn't good enough to save the batsman.
They must have something in contact with the ground behind the crease.
You can not be stumped off a no-ball, but you can be stumped if the ball is called wide.