Why does a flight fare change between search and booking?

Flight fares can change between search and booking because airline prices are updated in real time. The fare you see during a flight search depends on seat availability, booking class, travel demand, route popularity, taxes, and airline pricing rules. If another traveler books the same fare class before you complete payment, the system may automatically move to the next available price. Currency fluctuations and supplier inventory updates can also affect the final amount. A reliable flight booking API performs fare revalidation before confirmation, helping travel websites display the latest available fare and reduce booking failures caused by outdated pricing information.