IOS

iOS is an operating system made by Apple that was originally named iPhoneOS until iOS 4.0 due to the release of the iPad. It is considered the competitor of Android. However, iOS 11 ended support for 32-bit applications meaning that the free versions of all Angry Birds games except for Bad Piggies Free and Bad Piggies Free HD/Bad Piggies HD Free cannot be played on iOS 11 and later. Amazing Alex and most Angry Birds games can be installed on iOS.

iPadOS
iPadOS is the iPad version of iOS, originally being named 'iPhoneOS' until iOS 4 released, and then being renamed to iPadOS at iOS 13.

Angry Birds Game And App List
This is the list of Angry Birds games and apps available for iOS, including the iOS/iPadOS version required. iOS versions with to are inclusive.

HD And Free Versions
All of these are no longer avaliable (apart from Bad Piggies HD)

Trivia

 * Angry Birds Star Wars II Free is the only free version that is not on iOS.