A retail company has deployed Microsoft 365 Copilot. Employees notice that when they ask Copilot questions in Word or Teams, it can accurately reference their own recent emails, shared documents, meeting notes, and calendar entries to produce personalized responses. The AI transformation leader is asked to explain which underlying Microsoft technology enables Copilot to securely retrieve and reason over this organizational content while respecting each user's existing access permissions. Which technology should the leader identify?