All air tickets have fare conditions attached to them which determine the price of that ticket. The most common conditions to be aware of are those governing whether a ticket is refundable and whether additional charges will be imposed in the event that your travel plans change.
Different fares will have different conditions, and a ticket that allows you to change the dates of your travel without charge – or to receive a full refund if you cancel your travel plans – will be more expensive, but useful if you think your travel plans might change.
Be sure to ask your reservations agent about the fare conditions associated with the flights you are considering. If you are booking online, simply click ‘Fare conditions’ to view the rules relating to any given flight before adding it to your itinerary.