A market order is a trading instruction to buy or sell immediately at the best available current market price. Market orders prioritize execution speed over price control, guaranteeing fills but not specific prices. These orders are useful when immediate execution is more important than price optimization, particularly during fast-moving markets or urgent position management.

Market orders may experience slippage during volatile conditions as prices can move between order submission and execution. In illiquid markets, market orders might execute at significantly different prices than expected. Understanding market order risks helps traders choose appropriate order types based on market conditions and execution priorities.

Real-world example: A trader places a market order to buy 500 shares of Tesla during earnings announcement, accepting execution at $255.75 instead of the expected $255.00 to ensure immediate position establishment before further price movement.