A documentary aims to document and inform audiences about aspects of reality. John Grierson first coined the term "documentary" to refer to the creative treatment of actuality. There are several types of documentaries including fully narrated documentaries which use voiceover narration to help audiences understand events, mixed documentaries which use interviews and archived footage to advance an argument, and self-reflexive documentaries where subjects acknowledge the camera. Key features of documentaries include interviews with experts, observational footage, dramatizations of real events, and mise-en-scene techniques to frame shots effectively and support the documentary's argument.