Instagram has a huge community of around 800 million users, and most of them are very pleasant to interact with. In fact, Instagram is committed to fostering a safe and kind community. To show this commitment, Instagram recently added a feature to give their users control over who gets to comment on their Instagram posts.
If your account is public, you’ll now have a new way to choose who can comment on your posts. You can limit comments to:
1. Only people you follow
2. Only your followers, or…
3. Both your followers and the people you follow
Anonymous trolls need not apply here. In addition, public and private accounts can still disable comments completely on a post-by-post basis.
Via: Instagram blog