A note is a simple eRoom page for composing, editing, and sharing information without using or requiring other members to have another application to do so (example).
When you create or edit a note, its properties are
the title of the note -- required
the text of the note
whether members can add comments and take votes on the note page -- initially on
whether members can add attachments to the note -- initially on
the access control properties for the note
what the note's icon looks like
When you go to a note page, eRoom automatically scrolls to the first unread comment, if there is one.