iOS 9 How-To: Use the updated multitasking interface on iPhone and iPad | 9to5Mac
“Ever since Apple made the move to a more ‘flat’ design with iOS 7, the multitasking interface has changed in either a minor or major way with each iteration. With iOS 9, the interface has changed yet again. While the change is not hugely radical, it does take some adjusting to…”
Source: iOS 9 How-To: Use the updated multitasking interface on iPhone and iPad | 9to5Mac