Are market orders executed immediately?

Market orders are executed as soon as possible. This means that if the current market price matches the limit price of a market order, it is placed immediately on its scheduled queue among those waiting to be filled.

This is different than an immediate or "day-or-trade" limit order, which will not execute until your designated execution time or at the moment when the trade reaches your predetermined target level.

A market order specifies only one transaction type (buy or sell) and does not specify how many stocks you want to buy/sell nor the price you want the stock to trade for.

Market orders represent your decision to transact in any quantity desired at whatever prices exist in that specific window of time - so they're essential.

If you place an order when the market is closed, it will be executed when the market opens again. For the order not to be executed at a significantly different price, you should use a limit order. A buy limit order is executed at the limit price or lower, and the sell limit order is executed at the limit price or higher.