What recourse do you have when a flight is canceled or delayed, or the airline changes its schedule or loses or delays a checked bag or bumps you from a flight? Even though the U.S. Department of Transportation and European regulators promulgate and enforce consumer protections, there are probably fewer "fly rights" than you think, and these vary depending on the country you're flying within, to, or from; which airline you buy your ticket from; and which airline is actually operating the flight.
Delta's contract of carriage, which you agree to when you purchase a ticket, is typically restrictive concerning its obligations to passengers: "Published schedules, flight times, aircraft type, seat assignments, and similar details reflected in the ticket or Delta's published schedules are not guaranteed and form no part of this contract. Delta may substitute alternate carriers or aircraft, delay or cancel flights, change seat assignments, and alter or omit stopping places shown on the ticket at any time. Schedules are subject to change without notice. Except as stated ... Delta will have no liability for making connections, failing to operate any flight according to schedule, changing the schedule for any flight, changing seat assignments or aircraft types, or revising the routings by which Delta carries the passenger from the ticketed origin to destination."
Which doesn't mean you have no rights at all when you fly, so read on.