A new free iPhone app is dedicated to finding travellers the cheapest flight possible - by predicting the future.
Other price comparison sites work by giving you the best price currently available, but this app, called Hopper, uses historical data to tell you when is the best time to book your flights.
According to BGR.com, Hopper's Brianna Schneider wrote in a post on the company's blog: "Hopper predicts future prices by analysing historical price data and advance purchase curves for similar trips.
"Hopper's Price Prediction will advise you whether to book now or wait for a better price. It also provides a timeline of exactly how we expect prices to trend."
The post continues: "About a third of the time the current price is the best it's going to get, and the app will advise you to book now; more often, two-thirds of the time, the price for your trip will be lower at some point in the future.
"In 95% of cases, following the advice from the Price Prediction will get you a cheaper flight or at least the same price as found in your initial search."
The Telegraph Travel's consumer editor, Nick Trend, says it could be a good idea, but highlights some pitfalls.
"But it will need to prove that it can gauge and predict future fares, and there are lots of complications and pitfalls in doing this - such as the effects of one-off events on demand for flights, for example.
"The app is also currently showing fares only in US dollars - British users will want prices in pounds. So, it is worth looking at, but I would also check fares on other another app, such as Skyscanner, to be sure you are finding the best prices."
Why you should book a flight exactly 54 days in advance
10 tips on how to save loads of money on your next holiday