确认 (quèrèn) means 'to confirm, to verify' — it's used when you check and make sure information is correct, like confirming an order or meeting time. It differs from 确定 (quèdìng), which means 'to determine, to make certain' (often a decision), and from 证实 (zhèngshí), which is more formal and means 'to confirm with evidence or proof'.