What Is Market Order?

A market order is an order to buy or sell a stock at the current price the stock is trading in market. So when you place such order whatever price the stock is trading at, your order will get executed at that rate. So, suppose you placed market order for ABC, stock trading at 100, although it takes few seconds for your order to sent to exchange and it might happen that the stock price have fallen or rose to few points(100.40, 99.30 etc).

This happens because prices fluctuate ever microsecond. The latest-traded price also know as LTP in the market may have changed by the time you place (bid) your order. Generally, this type of order will be executed immediately. However, the price at which a market order will be executed is not guaranteed.