Screenshots are vital for debugging 'Headless' execution (where you can't see the browser visually). You use the `TakesScreenshot` interface to capture the current browser state and save it as a file (PNG, JPEG). Screenshots help identify what the browser saw when a test failed. In professional frameworks, screenshots are automatically taken on test failure and attached to the report.
Screenshots are like crime scene photos. When a test fails, a screenshot shows you exactly what was on screen at that moment, helping you understand why it failed.
How do you ensure a screenshot is taken only when a test fails?