What is United's overbooking policy and how does it impact passengers?

United Airlines' overbooking policy allows them to sell more tickets than there are available seats on a flight, in anticipation of some passengers not showing up. This can lead to situations where passengers are involuntarily bumped from their flight if there are not enough seats available. This policy can impact passengers by causing inconvenience, delays, and potential frustration if they are bumped from their flight.