

One of the more confusing distinctions for history students at every level is that between "primary" and "secondary" sources. This page is intended to provide a clear definition of what constitutes each type of source and to provide simple guidelines for distinguishing between the two.
As with any rule, there are exceptions to those provided below. This is especially true when dealing with the history of recent years, within the past 100 years or so. But for purposes of study and research in history prior to 1900, these guidelines will, I hope, prove informative and useful.
What is a "Primary" Source?
Generally, a primary source is one that was created at or extremely near the time of the historical events it describes. It is also usually the product of either the person(s) involved in the event or an eye-witness to the event. Primary sources can include not only handwritten documents and printed texts but also paintings, photographs, and physical artifacts.
Primary sources also include materials created at or near the time of the event but transcribed, translated, printed, and/or published at some later time, so long as the later version is an authentic and accurate "word-for-word" rendering of the original. Handwritten documents, for example, are sometimes published in printed collections by academic presses in an effort to make them easier for researchers to access and to read.
Types of Primary Sources include:
A legal document such as a will, contract, or property deed relative to a person or event
An individual's diary or journal
Letters between people and/or organizations
Court and governmental records relative to a historical event
Any of the above found reproduced "word-for-word" in a modern printed form
Examples of Primary Sources include:
The Last Will and Testament of Henry VIII (written ca. 1546)
The Diary of Grace Mildmay (d. 1620), both the handwritten original and the modern printed version
Letters to and from Heinrich Bullinger (d. 1575), both the handwritten originals stored at the Staatsbibliotek (Zurich) and the versions printed by Cambridge University Press in the nineteenth century.
This category of sources is actual easier to define and to understand. The rules that govern it are also less subject to exceptions. A secondary source is any item that was created significantly after the events it describes or is related to, or that was created by someone who was not directly involved in or an eye-witness to the events. Secondary sources also include simple descriptions of primary sources that do not reproduce the original "word-for-word."
Types of Secondary Sources include:
All biographies. A biography of an individual is never a primary source, though it may (or may not) be based on primary sources.
An account of an event written many years afterward. This can sometimes even include accounts written by eye-witnesses, especially if there has been a large lapse of time (e.g., a child's-eye view of the French Revolution written only when the child had become a sixty-year-old man).
I'm confused....
Don't feel bad! Even experienced graduate students in history sometimes get confused about the difference between primary and secondary sources and "argue" about whether a specific source is one or the other. I've participated in, and sometimes lost, many of those arguments myself.
But if you are working on a project for school and have questions about whether a specific source is a primary or a secondary one, feel free to contact me and I will try to help you figure it out, if I can.
Historian@somegreymatter.com
(copy and paste to your email program)