During each half of a network-televised game, there are ten prescribed commercial breaks following the official kickoff. Two are firmly scheduled, and eight others are worked in during breaks in the play.
Pre-scheduled commercial breaks:
The end of the first (or third) quarter
The two-minute warning of the second (or fourth) quarter
Other instances used for commercial breaks (eight total required per half):
A timeout called by either team
Instant replay stoppage
Game stoppage after a score
Game stoppage after a kickoff or punt (excluding the opening kickoff of each half)
Game stoppage after a turnover
Two commercial breaks during the typical 12-minute halftime period are considered separate.