A trailing stop order sets the stop price at a fixed amount at the market price with an attached "trailing" amount. As the market price rises, the stop price rises by the trail amount. If the stock price falls, the stop loss price doesn't change, and a market order is submitted when the stop price is hit.
Example:
Let's say you're going long on EUR/USD and you set a 50-pip Trailing Stop after buying at 1.2550. If the price rises to 1.2600, your stop would also rise from its initial level of 1.2500 to 1.2550 (50 pips). The Trailing Stop will then stay at 1.2550 unless the price moves another 50 pips in your favour.
Important to note:
❗️Trailing Stops are not available on mobile trading terminals (such as Android and iOS versions of MT4)
❗️Trailing Stop works in the client terminal, not in the server and it will not work if the terminal is off.
❗️Trailing Stop is processed once per tick. If multiple orders with Trailing Stop are open for one symbol, only the trailing stop of the latest open order is processed.