The very first thing users see when downloading an app these days is an onboarding screen. An onboarding screen is like a walkthrough, aimed to introduce what an app does to a user and of course how to use it. Thta’s the simplest way of describing it. Designing it however is a totally different thing.
An onboarding screen needs to be designed in the most simple, welcoming and user-friendly way possible. Onboarding screens like empty state pages created to inform and educate users. Not every app needs an onboarding screen although I think onboarding screens save users from the frustration of having to figure out on their own that new app they are trying out.
Goodbye, Windows 10 Mobile