Final answer:
Comments are added when reviewing a document to provide feedback, suggestions, or clarification on specific parts of the document. They help the reviewer communicate their thoughts and opinions to the author and improve the document.
Step-by-step explanation:
When reviewing a document, comments can be added to provide feedback, suggestions, or clarification on specific parts of the document. Comments help the reviewer communicate their thoughts and opinions about the document to the author. They can point out areas that need improvement, offer alternative ideas, or highlight positive aspects of the document. Comments also allow for a constructive dialogue between the reviewer and the author, helping to refine and improve the document.