Instagram has begun testing a way to share posts with a more limited group of friends. Called favorites, the feature attempts to improve on earlier social network friend lists, encouraging users to post more often by giving them more control over their audience. If it rolls out broadly, the feature could turn Instagram into the default place to share for more groups of friends — and reshape the social dynamics of Instagram in the process.
Before Instagram developed favorites, users tried to build versions of it for themselves. They created so-called “Finstagrams” — private Instagram accounts followed only a handful of their closest friends. Or they posted photos publicly and then deleted them after their close friends had acknowledged them with a like.
This is something I've felt should be standard across any mainstream social network: the ability to distinguish Friends from Followers so users have more control over what they share.