If a college football game is tied at the end of 60 minutes, it goes to overtime.
A coin toss decides first possession and each team gets one offensive possession starting at their own 25-yard line.
The object is to score, and then prevent your opponent from doing the same. If the teams remain tied, they each get another offensive possession.
Once they reach a fifth overtime period, teams run alternating two-point conversions instead of starting at the 25-yard line.