Joining vs Subscribing to groups

I need to make this more clear. Subscribing means there will be a section about new posts in the group in your daily community digest email. So you can unsubscribe from a group if you don't want to get a bunch of emails about new posts made there.

At this point, joining just means you'll show up in the members list. It doesn't do anything particularly special. There will be features in the future where group admins can restrict who joins, and also restrict the ability to post to members only. Also, once we have a ton more groups, joining a group will be a good way to mark it as a "favorite" and find your way back to it. For example, on the homepage we'll probably show a list of groups you've joined.