Which is a good use case for a user field?

A user field is designed to store user-specific information, which can also be utilized for permission and notification purposes in Quickbase applications. The most fitting use case for a user field from the provided options is to define the conditions under which a notification is sent.

When setting up notifications in Quickbase, you may want them to be tailored based on user attributes or assigned users. By using a user field, you can specify which user or group of users should receive notifications based on certain criteria, like changes to a record or specific events occurring within the app. This functionality allows for personalized notifications and enhanced communication within the application.

The other options, while relevant to Quickbase functionality, do not leverage user fields in their contexts. Creating a summary field pertains to aggregating data across related records, granting access involves permissions and roles rather than user identifiers, and sharing an app revolves around app distribution rather than individual user contexts.