Before entering a futures or options transaction, the exchange requires a minimum amount of money to be deposited into your trading account.  The money required to initiate a futures or options positions is referred to as the initial margin requirement.

While the initial margin is the minimum amount of money required to enter a trade, maintenance margin is the minimum amount of money that must be maintained in the account. If the money in your account drops below a certain level, your broker will make a margin call.  A margin call is a request by the broker for the account holder to deposit additional money into the trading account. This usually happens when the futures/options position in the account loses money.  The only position that will not require maintenance margin is a “long only” options position.  Buyers of calls or puts can only lose the money that is spent on the premium.