An iceberg order, also called a hidden-quantity or reserve order, is a large order that is displayed to the market in small visible slices while the bulk of the volume stays hidden. Each time the visible portion is filled, another slice is released automatically until the full size is complete.
The purpose is to reduce market impact: showing a very large bid or offer in the order book can move prices against the trader before execution finishes. Iceberg orders are common on institutional venues and some ECN-style platforms, and less common in standard retail forex accounts. They are not fully invisible, since repeated refreshes at one price level can be spotted by other participants.
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Order Types and Slippage Explained
Market, limit and stop orders trade price certainty against execution certainty — plus what slippage is, where it comes from, and what a stop-loss caps.