A blog post / web page “liking” system.
Users visit the page and can “like” it, much like here in Discourse forum or like the Medium clapping widget.
Building this with the Fission SDK
This would be a “Likes App”. When a person first interacts with the widget on the page, if they are logged in with a Fission account already, then you need to authorize the liking app.
If you don’t have a Fission account, you go through a flow of creating a new account, and then authorizing the liking app.
Then you’re back on the source page, and can see that the widget state shows that you’ve liked it.
If you squint, this could be a bookmarking system, a search index system, or any number of other things that follows this pattern.