What does it mean if a flight is described as oversold?

When a flight is described as oversold, it specifically means that the airline has sold more tickets than there are available seats on the aircraft. This practice allows airlines to maximize their revenue, anticipating that some passengers may not show up for their flight. Consequently, when the aircraft is ready for boarding, there may be more passengers than seats available, which can lead to situations where some travelers may have to be denied boarding unless they volunteer to take a later flight or if the airline offers compensation. Therefore, the description captures the essence of overselling as it highlights the imbalance between ticket sales and actual seating capacity on the flight.

The other options do not capture this specific scenario accurately, as they either imply a problem of low demand or suggest that flights are fully booked without accounting for the overselling practice.