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I have checked Google Flights and many other online OTAs, displaying flight fares for future dates (extending upto 1 year). How are these rates decided and from where these data come? Are these rates predicted by respective OTA, or they come from any GDS (Global Distribution System) by airlines themselves?
Also whether these rates change with time? I mean if I book a flight ticket today (18th April, 2019) for the departure at (11th August, 2019) in $100, then will this price of 11th August, 2019 departure, for same flight, remain same for all the days there after till 11th August, 2019?
Example of Google Flight calendar with flight fares: