Limit Order illustration
A limit order is an order to buy or sell at a specific price or better. Limit orders are not guaranteed to be executed.
When the Current Price (A) drops to the order's Limit Price (C) or below the order will execute automatically. The order will be filled immediately if the buying price is above or equal to the current price. Therefore, the buying price of limit orders must be below the current price.
Buy Limit Order
Sell Limit Order
1) The current price in the above graph is 2400 (A). If a new buy/limit order is placed with a limit price of 1500 (C), the order will not execute until the price drops to 1500(C) or below.
2) Instead, if the buy/limit order is placed with a limit price of 3000(B)which is above the current price, the order will be filled with the counterparty price immediately. The executed price is around 2400, not 3000.
Post-only/FOK/IOC/GTC illustration
Description
Assume the market price is $100 and the lowest sell order is priced at $101 with an amount of 10.
GTC:
A buy order priced at $101 with an amount of 10 will last until it is completed or you cancel it.
FOK:
A buy order priced at $101 with an amount of 10 is filled. However, a buy order priced at $101 with an amount of 30 can't be completely filled, so it's canceled.
IOC:
A buy order priced at $101 with an amount of 10 is filled. A buy order priced at $101 with an amount of 30 is partially filled with an amount of 10.
Post-Only:
The current price is 2400 (A). At this point, place a Post Only Order. If the sell price (B) of the order is lower than or equal to the current price, the sell order may be executed immediately, the order will be canceled. Therefore, when a sell is required, the price (C) should be higher than the current price.