With the new iOS 11 coming in September, 32-bit applications (meanings apps released before 2014 that haven't been updated since) will be dropped from Apple.
Your high-powered apps like Facebook, Insta and Twitter are obvs safe 'cos they get updated all the time, but it's game over for the older apps that haven't been updated.
The reason for the change is so that Apple can remove dated prods from the App Store and make way for the creation of new apps.
Apple has been sending future incompatibility notices to users and app developers since 2014 to either update or the apps will be gone forevs.
Bright side? At least you'll have more storage space without all those clunky apps!