What is a documentary?

I think a documentary film is a non-fiction, informative film that teaches the viewer a main lesson on the topic of the film. Some of the most talked about documentaries are ones that teach people about a certain topic, like how wildlife documentaries teach people about how certain animals live and how they survive. Another reason why documentaries are important is because they paved the way on how films are created now. Some of the earliest films could be considered documentaries because they show every day people in their every day lives. Lastly, documentaries need to interest the viewer. The the viewer watches a documentary that they don't find interesting, they most likely won't retain the information that they watched. Without documentaries, film wouldn't be where it is today, teaching the people of the world.