A market order is an order to buy or sell an asset at the current market price. It is an instruction given by a trader to a broker to execute a trade immediately at the best available price in the market. When a market order is executed, it guarantees that the trade will be filled, but not necessarily at a specific price. The price at which the order is executed may be different from the price that the trader initially intended to pay or receive for the asset. Market orders are typically used when speed of execution is a priority, and when the exact price of the trade is less important than the certainty of the trade being executed.