1. When you put an app in the background is it "killed" or its still active? If its active then how long does it stays active in the background?

2. Can the user return to the screen they left from when leaving the app (Not the homescreen)

Thank you!

1. If the app is in the background it's not killed. But it can't do any work. It sleeps, so to speak.
2. Yes. They can. In general, this is the default behaviour.

@Hatsushira - Thank you for the reply first of all! Second, I thought on iPhones you cant "kill" an app. It just goes to sleep and the system itself decides when to put it down depending on the battery and phone performances...or something like that.

In case you are right then if the application is put to "sleep" then for how long the app will be sleeping until the systems shuts it down? Because from my understanding no app can sleep indefinetly.

You can "kill" apps on the iPhone. Perhaps the behaviour you describe was in the past. I don't know. But I usually end my apps and none is sleeping in the background on my phone.

Every now and then I visit my mother and there are a lot of apps sleeping in the background. So I don't think they are forced to shut down when they sleep in the background.

There is a functionality on OS level when your app is using too much energy or CPU power the app is shut down by the OS. But if your app just sleeps in the background it isn't.

But to be clear, you can't do much work in your app when your app is in the background. If this is what you want to do. There are only specific background modes which are allowed. And the app will be killed if it uses too much power/CPU on OS level.

You can force quit apps in iOS, but you shouldn't. Unless an app is misbehaving, forcing it to quit offers no benefits and can even be detrimental.

Do not close iPhone and iPad 'background'… - Apple Community

Thank you everyone. Very helpfull info!