RAG is not trustworthy just because it retrieves documents. Users need to know which evidence supports an answer, which parts are uncertain, and when the system should have refused to answer.

This is the role of citations and grounding. A cited RAG system links claims to specific passages, pages, rows, timestamps, or source records. A grounded system checks whether those passages actually support the claims.

Grounding reduces unsupported answers, but it does not eliminate them. The model can cite the wrong source, overstate what a source says, miss contradictions, or quote a passage that is related but not sufficient. Citations point to evidence. Verification is what confirms the evidence actually supports the claim.

This chapter shows how to produce structured citations, verify support, compute confidence, teach the system to abstain, and detect unfaithful claims before they reach users.