Why do flights get overbooked?

Related questions

1. Do you have to go through security again for a layover?
2. Can you use Metrocard on path?
3. How long does it take to check in at Newark Airport?
4. Is LaGuardia or JFK better?
5. Do you go through security twice on connecting flights?
6. Were there any survivors of Flight 93?
7. Can a flight be Uncancelled?
8. How do I get from Newark Airport to New York City?
9. How long is Newark Airtrain?
10. How long does it take to get to Manhattan from Newark Airport?

Tags

1. #empty
2. #opportunity
3. #remains
4. #plane
5. #flight
6. #generate
7. #particular
8. #revenue
9. #airlines
10. #missed
11. #people
12. #passengers
13. #calculating
14. #meaning
15. #available
16. #percentage
17. #maximize
18. #overbook
19. #seats
20. #profit
21. #airline
22. #already