Uses of an online system include a target user and other users that are connected to the target users. The online system presents a content item received from a target user to the other users. The online system receives comments on the content item from the users and a selection of one of the comments from a user. The online system provides one or more types of actions (e.g., adding the comment to the content item or highlighting the comment) on the comment that the user can take. Upon receiving a selection of adding the comment, the online system modifies the content item to include the comment. Upon receiving a selecting of highlighting the comment, the online system associates a highlighting feature to the comment. The online system provides the modified content item or highlighted comment for display to the plurality of users.