Scrubs focuses on the unique point of view of its main character and narrator, Dr. John Michael "J.D." Dorian (Zach Braff) for the first eight seasons, with season 9 being narrated by the new main character Lucy Bennett. Most episodes feature multiple story lines thematically linked via voice-overs done by Braff. According to Lawrence, "What we decided was, rather than have it be a monotone narration, if it's going to be Zach's voice, we're going to do everything through J.D.'s eyes.

Source: Wikipedia.org