Documentary (noun)

1. A film or television or radio program presenting the facts about a person, event, or place.
2. A written or printed work presenting a factual description of a particular subject.

Origin:

Mid 19th century (in the sense 'relating to the recording of facts or events'): from french documentaire, from document 'written proof'. the current sense dates from the early 20th century.

Examples:

1. She watched a documentary about the history of the Amazon rainforest.
2. The documentary provided a fascinating insight into the lives of the people who lived in the remote region.
3. The documentary film crew followed the explorers on their journey to the South Pole.
4. The documentary was based on extensive research and interviews with experts in the field.
5. The historical society had a large collection of documentary evidence of the town's founding and development.