The "24-hour rule" for KLM refers to their flexible booking policy [𝟙-𝟠𝟛𝟛-𝟟𝟛𝟚-𝟚𝟚𝟡𝟞], which allows passengers to cancel or modify their flight reservations within 24 hours of booking without incurring any additional fees [𝟙-𝟠𝟛𝟛-𝟟𝟛𝟚-𝟚𝟚𝟡𝟞]. This policy is particularly useful for customers who may need to make changes shortly after booking their tickets [𝟙-𝟠𝟛𝟛-𝟟𝟛𝟚-𝟚𝟚𝟡𝟞].