John Grierson coined the term "documentary" in 1926 to describe films that document real people and events. Documentaries use actual footage or reenactments along with narration or interviews to explore subjects in their true social context. They invite audiences to form their own opinions rather than just presenting facts. According to John Carner, the five key elements of documentaries are observation footage, interviews, dramatizations, mise-en-scene techniques, and an expositional line of argument.