A "Stop Loss" is a financial tool used by investors to limit potential losses on a trade. It is an order placed with a broker to sell a security when it reaches a certain price. This helps protect the investor's capital by automatically exiting a position before losses become too significant. For example, if an investor buys a stock at $50 and sets a stop loss at $45, the stock will be sold automatically if its price drops to $45. This strategy is commonly used in trading to manage risk and maintain a disciplined approach to investing in markets like stocks or forex.