A refundable plane ticket costs more up front but generally lets you cancel before departure and get the fare back as cash to your original payment method, with easier (often fee-free) changes. A nonrefundable ticket is the cheaper, default fare: if you cancel voluntarily, the airline usually does not owe you cash—many main-cabin fares become a named travel credit or voucher, while basic-economy tickets may have no residual value.
Even a nonrefundable ticket can still require a full cash refund when the airline cancels or significantly changes the flight and you decline rebooking or a voucher, under U.S. DOT rules. U.S. bookings made at least seven days before departure also qualify for a full refund within 24 hours of purchase. Source: Navan glossary on non-refundable tickets.