A Good-Til-Cancelled (GTC) order is an order to buy or sell a stock that lasts until the order is completed, expired, or cancelled.
The maximum lifetime of any order is 28 days. Any order older then 28 days will be automatically canceled by the system and all reserved funds will be returned to your account.
An Immediate-Or-Cancel (IOC) order is an order to buy or sell a stock that must be executed immediately. Any portion of an IOC order that cannot be filled immediately will be cancelled.
A Fill-Or-Kill order is an order to buy or sell a stock that must be executed immediately in its entirety; otherwise, the entire order will be cancelled (i.e., no partial execution of the order is allowed).