Primary sources include the following:
- photographs
- historical documents such as a diary, census, video or transcript of surveillance, a public hearing, trial, or interviews
- tabulated results of surveys or questionnaires
- written or recorded records of laboratory assays or observations
- written or recorded records of field observations
- artistic and fictional works such as poems, scripts, screenplays, novels, motion pictures, videos, and television programs
Most often, primary sources used in Wikipedia are a form of illustration. They illustrate what reliable secondary and tertiary sources learn about the discussed topic. Illustrations are a valid part of any encyclopedia, but should not outdo the content based on secondary or tertiary sources.
[Text adapted from Wikipedia's Use of primary sources in Wikipedia.]