The itBit Exchange currently supports the following order types: Limit, Market & Post-Only. For a brief description of each, please see below:
Limit Order: A limit order is an order to buy or sell at a specified price or better. A limit order will execute immediately if it matches up with an existing offsetting order(s) on the order book, or it will rest on the order book if it does not execute immediately. Limit orders are good-til-cancelled meaning they will be live until they execute or until they are cancelled. You may or may not pay a fee on this order type, depending on if you are a maker or taker and what fee tier you're in. For more information on Maker vs. Taker please see here.
Market Order: A market order is an order to buy or sell at the best available price that will guarantee immediate trade execution. That is, a market order to buy will immediately execute against the lowest, most competitive sell order on the order book. Market orders will never rest on the order book and will execute immediately. There will always be a fee charged on these trades as market orders are always taking liquidity, the fee will depend on which fee tier you're in.
Post-Only Order: A post-only order is a type of limit order that will not remove liquidity from the order book upon being posted. That is, a post-only order will only post to the order book if it does not lock or cross with an existing offsetting order. If a post-only order is placed at a price level that would lock or cross with an existing offsetting order, the order will immediately cancel instead of posting. You may or may not pay a fee on this order type, depending on what fee tier you're in.