A primary source provides firsthand information, direct evidence, or original data on a topic. It is the material on which other research is based. Primary sources tend to be contemporary to the events or conditions under examination, but in some circumstances may be written or created at a later time (e.g. autobiographies, memoirs, or oral histories).
Examples of primary sources include original manuscripts, technical reports, diaries, memoirs, letters, photographs, drawings, posters, film footage, sheet music, interviews, government documents, public records, eyewitness accounts, conference proceedings, works of literature, statistical data, speeches, emails, tweets, and web pages.