Scott Keyes, a reporter for Think Progress and author of e-book "How To Fly For free," shared to travellers a trick that can help them save a lot of money on airfare.

Keyes considers this "hack" his favorite for getting cheaper flights. It is called "throwaway tickets," or "hidden city" ticketing.

"This one can be a huge money saver. You just have to know how to use it," Keyes said about his favorite throwaway ticket website Skiplagged.com, Business Insider reported.

Throwaway tickets are basically the practice of buying cheaper tickets to any unpopular destination that has a layover at your actual destination.

Travelling from New York to Chicago is expensive because it is a thoroughfare city. Using the technique, you can book a flight to an unpopular destination like Milwaukee, as long as it has a layover at Chicago. Even when you skipped the flight from Chicago to Milwaukee, the flight fare is still cheaper compared to a direct flight from New York to Chicago.

It's clearly a controversial travel trick. When Skiplagged.com became famous for helping travellers book flights through this style of ticketing, both United Airlines and Orbitz filed a civil lawsuit, Daily Mail reported.

For this trick to succeed, travellers should note that they cannot book round-trip tickets and they should not have any check-in baggage.