In general there are two types of stop orders: stop loss and stop limit.
A stop loss order is an order to sell a stock if it drops to a specified price, or to buy to cover a stock you sold short if it rises to a specified price. Once the stop is triggered, the order is executed immediately at the market price.
A stop limit order is an order to sell a stock at a specific price and no lower than that price if it drops to that price, or to buy to cover a stock sold short at a specific price and no higher than that price if it rises to that price. Once the stop is triggered, the order is executed only if it can be executed at the limit price or better. Be aware tht using a stop limit order when you are going to be away does increase your risk of possibly not getting out.