How future flight fares are gathered by Google flights? [duplicate]

Question

This question already has an answer here:

• Where does Google Flights get its data from? 1 answer

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:

Answer 1

Google Flights simply searches the available database of airlines, exactly the same as many other consolidators, like expedia, kayak, travelocity, whatever.

The only differences are the power and cleanliness of the interface, they have no specific interest in selling you specific flights where they get a higher commission, and you cannot even buy every flight from Google Flights - you might need to go to the airline.
It basically just gives you a well-done UI (which is open to opinion, of course).

None of the prices are fixed in any way; airlines change their prices continuously, and your search tomorrow - or in 10 minutes - might show different prices.