Comments are a way to communicate with your team and discuss Ideas, Posts, Evidence and Discovery tasks.
You can add a comment on any of these cards, edit your comments, and delete them if needed.
Though all members of a project receive notifications when comments are added, you can @mention a specific teammate in a comment. Simply type @ to show a list of your teammates, and select one from the list. This will allow you to directly notify this teammate that their attention is needed in your comment.
Learn how to add, edit, and remove comments here.