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 'iOS' until iOS 13 released.

Angry Birds Game List
This is a list of the Angry Birds games on iOS and their system requirements.

Trivia

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