Still don't fully understand Proxima
Proxima
You're an app developer. You build an app called 'space invaders'. People play your game on their phones. Proxima is where the high scores are stored.
Similar service "Parse". Mobile developers used Parse. Parse was bought by facebook. Facebook shutdown Parse.
All the mobile developers who's info was stored on parse, then facebook, now is gone

.
Lesson: They should have housed their data on their own server! Should have used Proxima.
--edit--
25 April 2013
"Facebook Buys Parse To Offer Mobile Development Tools As Its First Paid B2B Service"
https://techcrunch.com/2013/04/25/facebook-parse/
31 January 2017
"Facebooks Parse developer platform is shutting down today"
https://techcrunch.com/2017/01/30/facebooks-parse-developer-platform-is-shutting-down-today/
updated by @michael: 08/20/17 09:25:56PM