You can add followers to issues – users who are not assigned to the issue, but who follow it.
These users can view and comment on the issue. The Followers section appears under Assigned Users and Contacts. You can add both individual users and teams as followers.
You can’t add an assigned user to the followers of a given issue, and vice versa. Users added as followers can view the issue but can’t edit or delete it. They can add comments.
Followers will receive notifications related to updates on the issues they are following.