I booked an airline 'stopover' deal and got a free hotel. This is why it's one of the best air travel hacks.

Welcome to Istanbul sign.

Taylor Rains/Business Insider

• I experienced Turkish Airlines' "stopover" deal in Istanbul, which included a free five-star hotel.
• It's one of the industry's best travel hacks, so long as you understand the rules.
• Some airlines stop short of complimentary stays but offer discounts on hotels and tours.

Your layover doesn't have to mean sleeping on the airport floor or surviving on a $10 hot dog.

Some airlines offer "stopover"...