Typically this would be defined as someone who opens the app everyday.
However, you could think about it as there being a few levels of active users.
1. There are those who open the app daily and interact with posts on a regular basis. These would be what you consider your classically defined ‘active user.’ They probably use the app as one of their primary social networks to connect with people.
2. Then you have the people who open the app maybe once a week when they receive a push notification that catches their eye, or to check in on the newsfeed, or maybe to complete a simple action for some points. Whatever their reason is, they don’t open the app everyday but they’re still fairly active.
3. Then there are those users who open the app maybe once a month. They’re not very active because maybe they don’t have their push notifications turned on for whatever reason so they’re hard to reach and they only open the app when they see an email telling them to do something in the app. Or maybe they’re not getting from the app what they thought they would get from it so they check in occasionally, but aren’t engaged enough by what’s offered to stay on for very long or open it again in the near future. Whatever the case may be, these are your least active users and you should be actively taking steps to try and engage them more. You should also be experimenting with ways to get people who have deleted the app to re-download it from the cloud.