What a trailing stop is
A trailing stop is a stop-loss that automatically follows the price as it moves in your favour, staying a fixed distance behind. If the price keeps rising on a buy, the stop rises with it, locking in more and more of the gain; if the price then turns and falls by your chosen distance, the trade closes.
The appeal is that it lets a winning trade run while still protecting the profit already made, without you having to babysit the chart. The catch, explained below, is a real one that catches many beginners out.
The numbered steps in MetaTrader
Step 1: Open the trade first — a trailing stop can only be attached to a position that already exists.
Step 2: In the Terminal (Ctrl+T), go to the "Trade" tab and right-click your open position. Choose "Trailing Stop" from the menu.
Step 3: Pick a distance in points from the list (for example 15, 25, or 50 points), or choose "Custom" to type your own. This is how far behind the price the stop will trail.
Step 4: The stop now moves automatically in your favour as the price advances, and never moves backwards. To switch it off, return to the same menu and choose "Delete All" or "None".
The limitation you must know
In standard MetaTrader, a trailing stop is handled by the platform on your own computer, not by the broker's server. That means it only updates while MetaTrader is open and connected. If you close the platform or lose your internet connection, the trailing stop stops trailing and your protection freezes at its last level.
For that reason, many traders also set a normal, server-side stop-loss as a backstop. The trailing stop then manages the profit while you are watching, and the fixed stop protects you if your platform goes offline.
An honest risk note
A trailing stop set too tight will get knocked out by ordinary market noise, closing you early and often. Set too wide, it gives back a lot of profit before triggering. There is no perfect distance; it depends on how much the market you trade normally moves.
Like any stop, a trailing stop cannot protect against a price gap that jumps clean past it. It reduces risk and automates good habits, but it is not a guarantee against a larger-than-expected loss.