Stop & Stop-Limit Orders
A stop order lies dormant until the stock trades at or through the stop price, then becomes a market order; a stop-limit order triggers the same way but becomes a limit order instead.
A sell stop at 45 on a $50 stock limits damage if the price collapses — but in a gap down it may fill well below 45. That slippage-versus-certainty trade-off between stop and stop-limit is the tested nuance.