Market Order
In a Market Order, the broker or the trading destination is instructed by the trader or investor to buy or sell a stock immediately at the best prevailing price in the market. Market orders are therefore used when the certainty of execution of the order is a priority over the price of execution. A market order is the most common order used to purchase a financial security. In fact, if the investor doesn’t specify any order types, then in many cases, by default, the order type is set to be a market order. Also, because it doesn't contain any restriction on price and time frame in which order can be executed, a market order is also called an unrestricted order.
Also, there is some time difference (known as latency) between you submitting your order and the order reaching the trading destination. This can cause slippage, i.e. there could be a difference in the price you enter and the final execution price you get. In most cases, the difference is small. However, due to high market volatility, there can be a large difference between the price you targeted and the one you actually get.
Example: An investor places a market order to buy 1000 shares of XYZ stock when the best offer price is $3.00 per share. If other orders are executed first, the investor’s market order may be executed at a higher price.