Each episode of the show opens with a title screen and Kiefer Sutherland's voice-over saying "The following takes place between (hour) and (hour)" However, the first season of the show had a slightly longer intro, adding "...on the day of the California Presidential Primary." In addition, various episodes have featured the "Events Occur in Real Time" title.
For some of the narrated introductions, Kiefer Sutherland adds "My name is Jack Bauer and (today/this) the longest day of my life."
For the season finale of the first season, and many episodes in the following seasons, a warning for graphic violence was added.