Slippage is the difference between the expected price of a trade, and the price the trade actually executes at. Slippage often occurs during periods of higher volatility, when market orders are used. In forex slippage occurs when a limit order or stop loss occurs at a worse rate than originally set in the order. Slippage often occurs when volatility, perhaps due to news events, makes an order at a specific price impossible to execute. In this situation, most forex dealers will execute the trade at the next best price.