Documentaries use several codes and conventions to appear realistic and convince viewers that footage is unaltered. Voiceovers are often authoritative to position the filmmaker as an expert and shape audience opinions. Archive material and interviews with experts are used to authenticate the documentary's message. Sound, titles, and set-ups are employed to efficiently convey information and typical scenes, though some reconstructions may not depict true reality. Technical aspects like natural lighting also contribute to the realism effect.