A stop loss is an easy protection mechanism that you add to your order (either when you place your order or soon afterwards). Example: you want to buy EUR/USD at 1.3100, but want to make sure you don’t lose your shirt if the market goes south, so you would place a “stop loss” at 1.3000 so that if the market falls, you only lose 100 pips. The advantage is that it exits your order automatically, you don’t have to sit there monitoring the market (and you’ll be happy to have used a stop loss if your internet connection or computer experiences a malfunction!). ALWAYS use a stop loss with all of your orders, even when you’re scalping.