Most travelers know that cheap airline tickets come at a price—you can'tcancel the trip or change your travel plans without paying a hefty penalty.What many airline customers don't know is that you can cancel or changeyour plans without any charge—if you act quickly. Most of the nation's majorairlines give you 24 hours to turn your ticket in for a refund or exchange it for adifferent itinerary without penalty. Each airline has different rules, so it pays tocheck when you book the ticket. For example, United Airlines will let youcancel but not change a ticket. Cancel the ticket and start over for yournew destination. Online travel agencies like Orbitz and Travelocity mayimpose their own cancellation fees even if the airlines don't charge you.