A day order is a type of order, or instruction from a trader to their broker, to buy or sell a certain asset. Day orders require that a deal is executed if an asset hits a specified price (referred to as the level) at any point during the trading day on which the order is made.
The day order will expire if the price specified in the order is not met by the asset by the time the market closes. There are two different types of day order: stop day orders and limit day orders. If the price at which the trade will be executed is more favourable than the current market price then it is a limit day order, if it is less favourable it is a stop day order.
Day orders differ from GTC (good-‘til-cancelled) orders, or orders that specify a longer or shorter time period for execution. Most brokers and trading platforms tend to use day orders as the default means of trading, meaning that a trade will expire if unexecuted after a day unless a different time span is specified.