Market order: the user does not set the price of the order, but only the quantity/amount of the order, and the order will be filled from the best price in the market until the order quantity is completely filled.
Generally, market order will be filled immediately, and may generate price slippage when the order quantity/amount is large.
Limit order is an order to buy or sell at a specific price.
A limit order is not guaranteed to execute. If you want your order to be filled as soon as possible, please refer to the order book and set a competitive price, or simply choose a market order.
What is GTC，FOK and IOC?
Bit.com offers three different options for limit order, which are Good Till Cancel (GTC)，Fill Or Kill（FOK），Immediate or Cancel（IOC）.
Good Till Cancel (GTC)
A good till cancel (GTC) order is a type of limit order that is placed by a trader to purchase or sell at a particular price which remains active until it’s cancelled by the trader. The default option of limit order on Bit.com is GTC.
Fill Or Kill（FOK）
A fill or kill (FOK) orders must be filled immediately and completely at the limit price or better, or not at all, which means FOK orders are not allowed to be partially filled.
Immediate or Cancel（IOC）
An immediate or cancel order (IOC) is to buy or sell at the limit price that executes all or part immediately and cancels any unfilled portion of the order.
A Post-only order will only allow your order to be posted when it can enter the order book. In other words, post-only orders ensure that you will always be a maker. If your post-only order will be filled immediately with an existing order, then your order will be automatically repriced.
As shown below, Amy plans to open a short position of BTC perpetual swap worth $100 at the price of $36,400.
If Amy does not select [Post Only], according to the current order book, her order will be immediately filled with the buy one price (36,487.00) in the order list.
If Amy selects [Post Only] mode, Amy's short order will be automatically repriced to a higher step than the highest bid: 36,487.50 (i.e. 36,487.00+0.50), which is shown in the order book (the lowest ask).