A market order is a basic trade order that instructs to buy or sell at the best available price. Market orders are considered to be the most immediate way to enter or exit a trade and it often executed instantaneously.
Fast execution is the best way to describe market order, it usually execute a trade almost immediately. Another main advantage of using a market order is that allow the trader guarantee to fill the trade. If a trader needs to get in or get out of a trade, then a market order is the most urgent order type.
However, there are also some disadvantages of a market order. For example, a market order cannot guarantee the price of the trade, thus trader should not expect any precision when placing a market order to the market. In a highly liquid market like the Bitcoin futures, market sell orders will generally fill at the bid price and market buy orders at the ask price, but it is not always the case even through in a liquid market.
In this fast moving market, a market order can result in slippage, means the differences between the price a trade expected and the price where the trade is actually filled. Using market orders exclusively on the field with strong liquidity can help avoid slippage which can be the difference between the winning or losing trade.