Market Order vs Limit Order
A market order executes immediately at the best available price; a limit order only executes at your specified price or better. The choice between them involves a trade-off between certainty of execution and certainty of price.
A market order instructs the broker to fill your trade as quickly as possible at whatever price is currently available. You are guaranteed execution (assuming liquidity exists) but not the exact price — in fast-moving or illiquid markets this can lead to slippage, where the fill price differs from the quoted price at the time you clicked.
A limit order specifies the maximum price you are willing to pay (for a buy) or the minimum price you will accept (for a sell). The order sits unfilled until the market reaches that price. If the price never reaches your limit, the order remains open or expires.
Stop orders are a third type: a stop-market order triggers a market order once a specified price is reached, often used for stop-losses. A stop-limit order triggers a limit order at the stop price — but carries the risk of non-execution if the price gaps past the limit level.
The practical choice: use market orders when getting into or out of a trade quickly is more important than the exact price (e.g., news-event trading or closing a losing position). Use limit orders when you have time and a specific price level in mind.