Background info, usually found in reference sources is invaluable.

Reference sources provide the following types of information on virtually any topic:
- Reliable background information;
- Articles written by subject experts;
- Dates, timelines, events, people related to your topic;
- Biographical information;
- A list of further readings, normally found at the end of encyclopedia articles. Use these references as springboards for further research.
Image source: Leonardo da Vinci, Mona Lisa, 1503-1506. Wikimedia, Public Domain.