With limit orders, you will specify the price you wish to transact. If you are buying, you are instructing your broker to buy at no higher than the specified price. If selling, you are telling him to sell at no less than your stated price. The advantage of using limit orders is that you are in full control of the price at which you buy or sell your options. The disadvantage is that filling the order will take some time, or the entire order may not get filled at all because the underlying stock price has moved way beyond your desired price.