Stop-loss
An order that closes a position once a loss level is reached. A risk-management tool — not a guarantee of the exit price (gaps, slippage).
Definition
A stop-loss is an order (or a rule) that closes a position once a defined loss level is reached. It is a tool inside a risk-management process — not a guarantee of an exact exit price (gaps, slippage and a broker stop-out can all produce a worse fill).
Example
Long at 100, stop below the swing at 97. Risk per share = 3; you choose the number of shares so that 3 × size ≈ 1–2% of capital. If the price falls to 97, you exit and record −1R instead of “waiting it out”.
Anti-example / common mistake
Moving the stop further away when the market goes against you (“give it a bit more room”). Or trading without a stop at high leverage and assuming you will “get out in time by hand”.
The process (1R)
The stop defines the risk distance → size is calculated from the risk in PLN, not from “how many lots the margin allows”. On CFDs and futures a gap or a news event can produce a fill worse than the stop price — plan a psychological and capital buffer for that. In your journal record the planned 1R and the realised result in R (after slippage).