Primary and Secondary Sources

To judge the usefulness of a work, you should know the difference between primary and secondary sources:


Primary Source: A work that is itself the subject of your essay or (if you are writing a historical research essay) a work written during the period that you are writing about that gives you direct or primary knowledge of that period.

Examples: the Constitution, legal documents, memoirs, diaries, a work of literature, etc.


Secondary Source: Any commentary written both after and about the primary source is a secondary source.

Examples: history textbook, Times book review, encyclopedia reference, etc .