'Purpose of registering a domain when applying for a key to authenticate with a service using OAuth2?

Probably a stupid question - I'm interested in building a mobile app that authenticates with a service using OAuth2 so that my app can use their API's. Documentation

To apply for an application key, I need to enter my application's domain name. What does this mean for my case? I am not building a website where users of my site will sign in to this service, I just want users of my mobile app to be able to get information from the service's APIs, using their account on that service. I don't understand what domain name would be required in this scenario.



Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution Source