Historians use both primary and secondary sources in interpreting past events. Primary sources are first hand. Illustrations, letters, diaries, recollections, objects and other documents from the era can provide facts as well insight into how people at the time thought and lived. Primary sources are the foundations of all historic research. They are the threads that make up the study of history.

Secondary sources are interpretative, usually written afterwards. Histories and textbooks, for example, are secondary sources. Weaving together the threads of the primary sources, they tell a story which creates the cloth of history—whether it be solid, stripped or plaid. They are always influenced by the author's point of view, interests, background, prejudices, and knowledge. What documents an author chooses, how the author uses them, and—most importantly—how the story is told can vary. The facts may be the same but history changes because there are many different interpretations of past events.

Historians often use secondary sources to place the primary sources in context. No one will ever completely understand the past. It is gone…lost to us forever. We can, however, try to reconstruct it. Reconstructing the past is difficult and involves a number of disciplines, or points–of–view. They can help by giving us information we don't see or that we may not have readily available. They can provide the place where we put our facts and determine whether the clothes we dresed them in are appropriate or not for the setting.