Comments are a way to communicate with your team and discuss idea, post, evidence, research or experiment cards.
You can add a comment on any of these cards, edit these comments, and delete them if needed.
Though all members of a project receive notifications when comments are added, you can call out to 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.