The 24-hour rule for KLM means that if you book a flight with KLM and then need to cancel it, you can do so for free within 24 hours of booking. This rule applies to all tickets, no matter what type you bought. It gives you a chance to make changes or cancel if you made a mistake or changed your mind about your travel plans. After 24 hours, regular cancellation or change fees may apply depending on the ticket conditions. This policy is helpful for travelers who need flexibility in their plans.