Comments in Designer are an essential tool for collaboration of multiple users working on the same questionnaire. Each of the collaborators may leave comments to questions, indicating potential problems in implementation, or suggesting improvements. For example, It is common for the reviewers, that have a shared access to a questionnaire to leave the comments for the original author.
The full list of comments in all sections of the questionnaire can be seen in the comments tool, which is accessible from the toolbar. Often the comments represent a kind of to-do list:
Comments can be marked as resolved, but even resolved comments are still recorded with the questionnaire.
A questionnaire can be shared by inviting users from the questionnaire's settings dialog.