"What If Events Arrive Out of Order?"

What They're Really Testing The Unlock The mental model: event time tells you WHEN it happened. Processing time tells you WHEN YOU LEARNED about it. A click at 2:00 PM that arrives at 5:00 PM should be counted in the 2:00 PM window, not the 5:00 PM window. But how does the system know the 2:00 PM window is complete if events are still arriving for it at 5:00 PM? That is the watermark problem. 15% The 60-Second Framework Step 4 is the strong-hire signal. The latency-correctness tradeoff is the central tension in streaming systems. Naming it unprompted shows you have operated real streaming pipelines, not just read about them.