Diegesis In fiction , diegesis is that part of an entertainment which is obviously part of the narrative itself . In film and television , something is said to be diegetic when it is experienced by the characters . The term is seen with some frequency in literary criticism , as the concept dates back to the ancient Greek notions of drama . People who are more casual about the concept generally equate " diegetic " with " in - universe " and " extra - diegetic " with " out - of - universe " . Examples from the DWU . Narrator . A diegetic narrator is a narrator who is part of the events of the piece , as was Gwen Cooper in " " or Ian Chesterton in " " . An " extra " - diegetic narrator is one who is " not " a part of the action , like Tom Baker on the VHS release of " Shada " , or Carole Ann Ford on the VHS release of " The Reign of Terror " . Music . The term has great applicability with regard to an episode ' s soundtrack . Incidental or theme music is almost always extra - diegetic . The Eleventh Doctor can ' t hear " I Am the Doctor " , but the audience can , every time the Doctor does something heroic . The Tenth Doctor didn ' t hear " Vale Decem " when he regenerated , but " we " did . Equally , Martha Jones couldn ' t hear " Sunshine " or " Martha ' s Theme " , so they ' re all extra - diegetic . Sometimes , though , songs " are " heard diegetically . John Smith and the Common Men provided the programme ' s introduction to diegetic music , as Susan was listening to their music in the first episode . " Ticket to Ride " followed the next year , and then came the programme ' s first " original " diegetic song , " The Ballad of the Last Chance Saloon " . Other songs like " Paperback Writer " followed , though as the programme drifted away from Earth , so too did its opportunities for diegetic music . The tradition has revived somewhat under Murray Gold , who ' s included a variety of original songs . Some , like " Song for Ten " and " Vale Decem " have been extra - diegetic , while others , like " Abigail ' s Song " and " My Angel Put the Devil in Me " have been plainly heard by the characters . Why diegesis matters to this wiki . To the casual audience member , it doesn ' t matter greatly whether a song is heard on a radio that ' s established as being switched on , or whether it ' s just a part of the incidental music . It ' s enjoyed — or not — either way . However , the editors of this wiki must take care to correctly note whether something is diegetic or not . The from which we write articles or the categories in which we place them changes greatly depending upon whether the article is about a diegetic or extra - diegetic element . For instance , " Abigail ' s Song " is actually in songs , while " Vale Decem " belongs to incidental and theme music . We should write " The Ballad of the Last Chance Saloon " initially in the past tense and then include a " behind the scenes " section at the bottom . But " Song for Ten " is " entirely " written from a real world perspective . Likewise , if Carole Ann Ford ' s VHS narration of the missing parts of " The Reign of Terror " is at odds with the " narrative " as restored by 2 | entertain on the DVD , her recounting is deemed inferior information , because it is not diegetic .