VTC: is short for Valid Till Cancellation, which means once the order is placed it will stay open even if it is partially filled and will only get canceled after 7 days if the remaining order does not find any match.
IOC: is short for Immediate Or Cancel, which are executions where the remaining orders will be canceled instantly for e.g the order is matched and only 75% filled, then the remaining 25% will be canceled immediately.
POST: is orders that are simply only the maker’s orders whenever executed. If the order tries to match with an existing order from the order book, it will be cancelled. If it doesn't match with an existing order, it will stay open for up to 7 days. POST orders can't become takers in the order matching process.
Extra clarification: a maker is when a user enter an order that goes into the order book as being open and pending to be matched up with someone who is trading as a taker and the trading price is moving in the direction of the maker order to get filled.