Notes
Somewhere to put a thought that does not belong to a record yet.
What they are
Short, personal, and yours alone. Nobody else in the project can read your notes, including the project's owner — they are the margin of your notebook rather than part of the book.
Tags and search
Notes take tags, and the list filters by them. There is no folder structure on purpose: a note you have to file is a note you will not write.
References
A note can point at a record — a character, a chapter, a location. The reference is a real link: open the note later and you can get to the thing it was about, and the record shows that a note refers to it.
This is the feature that makes notes worth keeping rather than a second inbox. "Ask whether she would really say this" is useful attached to the character; on its own, in a list, it is noise in a week.
Archiving
A note can be archived rather than deleted, which takes it out of the list and keeps it findable. Deleting is permanent.
What happens to them
Notes are personal data rather than project content, so closing your account deletes them — unlike the chapters and characters you contributed to somebody else's project, which stay with the project. See account and security.