How does an app store user data?

Question

Such as Facebook, Sololarn and PUBG etc.
How they store our information. What language do they use?

Answer 1

There are various combination used like JS Hack php python java etc
https://en.m.wikipedia.org/wiki/Programming_languages_used_in_most_popular_websites

Answer 2

https://www.sololearn.com/Discuss/999579/?ref=app

Answer 3

what language they use?

Answer 4

facebook has A LOT of data
https://www.datacenterknowledge.com/data-center-faqs/facebook-data-center-faq
i would think they use multiple languages to manage it but i dont work at facebook!