You have an on-premises app named App1 that accesses Azure resources by using credentials stored...

https://docs.microsoft.com/en-us/azure/active-directory/develop/app-objects-and-service-principals " When you ' ve completed the app registration, you ' ve a globally unique instance of the app (the application object) which lives within your home tenant or directory. You also have a globally unique ID for your app (the app or client ID). In the portal, you can then add secrets or certificates and scopes to make your app work, customize the branding of your app in the sign-in dialog, and more. "