Stop Order
An order that becomes a market order once the asset trades at or through a specified stop price.
A stop order (also called a stop-market order) is inactive until the market touches your stop price. At that point it converts into a market order and fills at the next available price.
Because it triggers as a market order, execution is guaranteed once the stop is reached, but the fill price may differ from the stop price — especially in fast or illiquid markets.
Stop orders are used both to limit losses (stop-loss below a long position) and to enter breakouts (buy stop above current price).
On the desk
You own XYZ at $50.00 and place a stop order at $47.00. If XYZ prints $47.00, the order triggers and you sell at the next market price — say $46.90 in a fast market.