Primary sources enable the researcher to get as close as possible to what actually happened during an historical event or time period. Primary sources can be diaries, letters, autobiographies, manuscripts, photographs, speeches, interviews, artifacts, government documents, newspapers, maps, census data, statistics, business records, court records, and original compositions, poetry, and artwork. Remember that because primary sources are often firsthand accounts that reflect the viewpoint and memory of a participant or observer, the information may be biased or skewed.
Secondary sources are usually written some time after an event has taken place. They are created by authors who have examined a subject and have drawn certain conclusions about it. Though the information is not firsthand, secondary sources are important because research, by necessity, is built upon the work of other scholars. Biographies, scholarly books, and journal articles are examples of secondary sources. As with primary sources, many secondary sources are also subjective and contain bias.
It is not always easy to determine if a source is primary or secondary according to the definitions provided. Sources are characterized by their content, regardless of their format. In other words, you must think about the information itself rather than the "package" it comes in. Additionally, a source can be both primary and/or secondary, depending on the context in which it is used. Primary sources can often be found embedded within secondary sources. Furthermore, the definition may vary depending upon the academic discipline. For example: