The stop loss is a key tool in trading that allows you to automatically limit losses. It consists of an order that is triggered when an asset reaches a specific price, closing the operation to avoid further declines. For example, if you buy a stock at $100 and place a stop loss at $90, the sale will be executed if the price drops to that level. It is useful for managing risk, protecting capital, and avoiding impulsive decisions. It can also be used to secure profits with a "trailing stop". It is essential to define the stop according to your strategy, risk tolerance, and technical analysis of the market.