A market order is a request to buy or sell a security at the best available price in the current market. It is widely considered the fastest and most reliable way to enter or exit a trade and provides the most likely method of getting in or out of a trade quickly, filling nearly instantaneously. The trade-off, however, is that market orders fill at a price dictated by the market, as opposed to limit or stop order, which provides you with more control. Using market orders can sometimes lead to unintended, and in some cases, significant costs.
A limit order is an order placed with a broker or exchange that allows you to execute a buy or sell transaction at a set number of shares and at a specified limit or instrument price. It is an order placed with a broker or exchange to buy or sell a set amount of a financial instrument at a specified price or better. Keep in mind that limit orders are not market orders, it may not be executed if the price you set cannot be met during the period in which the orders are left open. Limit orders also allow you to limit the length of time an order can be outstanding before being cancelled.