"Primary sources are the forms of evidence contemporary to the event or process described. Although secondary evidence is essential to the historian, primary sources are the stuff from which history is written."
Doing History; Researching and Writing in the Digital Age. 2nd ed. M. J. Galgano, et al. Wadsworth, 2008. pp. 5-6.
Generally speaking, primary sources are created during the time of the topic or event under study. There are many kinds of primary sources including texts (letters, diaries, government reports--tax records, census materials, hearings, maps--official records, newspaper accounts, novels, autobiographies, memoirs), images (photographs, paintings, advertisements, posters), artifacts (buildings, clothing, sculpture, coins) and audio/visual (songs, oral history interviews, films).
For information on how to find specific types of primary sources see the sections on: