Order Types and What Each One Does to Your Queue

Each order type interacts with the queue differently, and choosing the wrong one can cost priority a trader did not know was at risk.

Every order type available on a modern exchange changes queue behavior in a specific, mechanical way, and choosing between them is a decision about priority as much as price. A limit order joins the queue and waits. A market order skips the queue entirely. Everything else on the menu sits somewhere between those two extremes, trading off certainty of execution against the priority a resting order can build.

A limit order rests at its stated price if it cannot trade immediately, and it holds its place in the queue for as long as its price and size stay unchanged. It is the default building block of the order book, and every other order type is really a variation on how and when a limit order is allowed to rest.

A market order never rests. It takes whatever price is available, walking through price levels until filled, and it carries execution certainty at the cost of price certainty. A trader who needs to be out of a position immediately accepts this trade-off deliberately.

A marketable limit order sits between the two. It is priced through the current best opposing price, so it behaves like a market order for the quantity that can trade immediately, but any unfilled remainder converts into a resting limit order at its stated price rather than canceling outright.

An immediate-or-cancel order executes whatever quantity it can against the current book the instant it arrives, then cancels the remainder rather than resting. It never joins a queue, which makes it useful for testing liquidity at a price without leaving a trace behind if the fill is only partial.