What does limit order mean?
Limit orders are a way to buy or sell a financial instrument, to enter or exit a trading position. With a limit order, you specify the exact price you are willing to pay and agree to wait for that price or better. You also accept the possibility your order might not get filled.
The other type of order is a market order. This is the most immediate type: you buy or sell at the best price that's currently available.
You can use both order types on Nadex.
When should you use a limit order?
If you want to set a profit target at which to exit your trade, you can use a limit order to specify the exact price at which you want to exit. However, you’ll have to wait for the market to reach that price or better. If and when the market reaches your target, your order will execute automatically. You should also bear in mind that the market may not reach your target price in time, prior to expiration.
You can't set a stop-loss target with a limit order, however. If you try, you'll get filled at that low price right away and be knocked out of the trade.
In summary, you should use a limit order to name your price, knowing you may need to wait and you might not get filled.