Grounding
Grounding is supplying a model with trusted source data in the prompt and instructing it to answer only from that data.
Analogy
Like telling someone to answer only from the open textbook in front of them, not from memory.
Why it matters
It reduces hallucinations in automated replies by tying Claude's answers to your real business data instead of its training guesses.
In practice
Pasting a contact's order history and asking Claude to answer using only those records.