Comments are used if necessary to keep a history of changes. You can enable Comments for any entities in your application.
On the page General Configuration->Comments enable comments for the selected entity.
On the Access comments page, configure the user groups that will have access to the comments.
On the page "Setting the form of comments" configure which fields, the values of which can be changed when adding a comment. The history of changes in field values will be saved along with the comment.