Most airlines provide different fare classes with varying restrictions or flexibility, which determine the amount you will be charged when cancelling your flight. Typically, cheaper fares have higher cancellation or amendment fees while premium or flexible fares come with lower or no fees.

To give you an idea of what to expect, here are some general policies regarding cancellations that airlines commonly follow:

1. Refunds - Depending on the airline, if you cancel your flight within 24 hours of booking, you may be eligible for a full refund with no penalty fees. After this period, most airlines will start charging cancellation or amendment fees.
2. Cancellation fees - The fees you will be charged depend on the airline, the fare class, and how close you are to the departure date. Generally, the closer to your travel date, the higher the fees will be. Some airlines may offer a partial or full refund if you cancel due to qualifying reasons such as illness or family emergency.
3. Amendment fees - If you want to change the dates, times, or destination of your flight, most airlines will impose an amendment fee. Once again, the fee will vary according to the airline and fare class.
4. Non-refundable fares - Many low-cost airlines offer non-refundable fares, which means that if you cancel, you will not receive any refund. However, you may still be able to receive credit to use towards another flight within a specified timeframe.

It's essential to check with your airline's cancellation policy before booking your flight to understand their fees and restrictions. Additionally, many airlines provide travel insurance that can help protect against unexpected cancellations due to illness, weather, or other unforeseen circumstances.