iOS: Having an elaborate, secure password on your Wi-Fi network can be a great thing. A great thing until that weekend you have guests visiting from out of town and they have to try your 20-character Wi-Fi password a dozen different times because a zero looks like an O or they couldn't tell from your chicken scratch which letters are capitalised and which aren't.
With iOS 11, sharing that password just got much easier. That is, if you and all your friends happen to be using iOS devices running iOS 11 or computers running macOS High Sierra. You'll also need to have their contact info saved in your device's address book.
Now when your Apple-loving friend tries to join your network, they can hold their phone next to your phone or computer that's already connected to the network and you can just share the password with them.
On your phone, you'll see a push notification letting you know that "Bob's iPhone 7" is interested in joining your network, and asking if you'd like to share the password. If you hit the big "Share Password" button on the dialogue box, the password with be auto-populated on Bob's phone without either of you having to type anything in. Bonus points: That means you don't actually have to tell them what your password is, just in case you use that same password, or variations of it, for other things.
On a Mac, that notification will happen in the top-right corner of the screen.
Sure, if your Wi-Fi password is "HouseInternet", this one isn't exactly a game changer. However, if your password is "HouseInternet", you might want to rethink that.