Glossary
Citation grounding
Binding each sentence of an answer to a source the system actually retrieved.
An answer can mention a document without having used it. Grounding is the stricter idea: the sentence is attached to a passage that was retrieved, and you can open that passage. Without the attachment, you have prose. With it, you have a check.
Cairn puts a citation on every sentence and shows source age and confidence beside the work. If sources disagree, it flags the conflict rather than hiding one of them. Try it with a question you can also answer by opening the note, as in Search your notes with citations.