How would you explain CAP theorem in a system design interview?

i'm finding myself struggling to explain the CAP theorem clearly and concisely in system design interviews. i understand the concept academically, but articulating it in a way that shows practical application and trade-offs in real-world systems feels elusive. when do you explicitly choose CP over AP, or vice versa? what are some concrete, well-known examples that illustrate these choices effectively? how deep do interviewers typically expect you to go into the underlying theory versus practical implications? any tips on structuring an answer that hits all the right notes without getting bogged down in jargon?