Prominent or known person appears briefly — usually unexpected moment. Hitchcock with cameos in his own films, or Oscar legend speaking three lines in a thriller.
A familiar face appears — three seconds, one line, then gone. That's a cameo appearance, and it only works if the audience doesn't expect it. The impact comes from surprise, not duration. On set, this means the prominent person arrives for half a day, plays a tiny role, and everyone knows this moment will be golden in the edit. Hitchcock perfected this — his brief appearances in his own films became his trademark. The audience searches for him before the credits roll.
Directorial craft for a cameo differs fundamentally from normal scenes. You have to stage the moment so it stands out without being intrusive. Often, a close-up is enough, a cut that establishes eye contact with the camera. The camerawork must be subtle — don't move in too quickly, don't linger too long. It's about the punchline, not the performance. Some directors incorporate these appearances like visual gags: a second in the background, and those who are paying attention will see it. Others do it more overtly — a famous voice on the radio, a photo on the wall, or that one unforgettable fragment of a line from an industry legend.
The dramaturgical function is marginal, but psychologically valuable. Audiences talk about it. They look for it on a second viewing. That's free word-of-mouth. In the edit, this moment is isolated, not integrated into the rhythm of the scene — it sits there like a foreign body, intentionally. Timing is crucial: too early in the film, and no one recognizes it; too late, and attention wanes. A cameo usually works best in the last third, when the audience is ontologically invested in the story and doesn't expect to be pulled out of it.
Practically, this means: the casting department handles travel, costume gets one minute of preparation, and the editor must know that this take doesn't fit normally — isolated, perhaps with different sound design, definitely with that moment of recognition in the viewer's mind. Related to this is the cameo as a production detail — see also Diegesis, Editing Rhythm — but the cameo appearance is the visible mark of it.