Stop-losses are used in dynamic trades to eliminate major and uncontrollable losses. If you don't use stop-losses, it's just a matter of time before a big losing stake spirals out of reach, wiping out the majority of your trading gains, and potentially your whole portfolio!
If you want to stay in the game and expand your trading account in the long term, you must use stop-loss orders in every single trade you make. The first rule of this article is to always use stop-losses.