Trailing Stop
The trailing stop is an important function in open positions. When you open a trade, you set the Stop/Loss on a particular pip value at the opening price for this trade. If this position is now running into positive, then you should tighten the Stop/Loss according to the increase. The trailing stop will do this for you
If you e.g. buy a position EUR/USD at the rate of 1.300 and set the Stop/Loss to a 30 pips, and the Trailing Stop accordingly also to 30 pips, then is the Stop/Loss is always at 30 pips from the highest price from the opening of trading. When the price rises so to a high of 1.360, the stop / loss is now 1.330 and not 1.2970 as at the opening.
In this way you are sure that a position, when it reaches a certain peak, no longer closes negative. It also relieves you of the, often false, decision, a position a little longer to keep them open so as to regain more profit.
In the MetaTrader4 trading platform you set the trailing stop with the right mouse button on the corresponding position and then click in the appearing menu below trailing stop to enter a preset value, or set to a click on the "Custom" the desired value.