To truly understand how a user became a customer, you need to see their path. Standard queries only show totals. Window functions like LEAD and LAG allow you to see the exact sequence of events.

SELECT 
  user_id, 
  event_name, 
  LAG(event_name) OVER(PARTITION BY user_id ORDER BY timestamp) as previous_step,
  timestamp - LAG(timestamp) OVER(PARTITION BY user_id ORDER BY timestamp) as time_diff
FROM events;

This query reveals the 'friction points'—where users spend the most time before completing a conversion.