This guide will introduce students to three types of resources or sources of information: primary, secondary, and tertiary.
Primary sources are firsthand documents that provide direct evidence on your topic.
The Library of Congress refers to them as the "raw materials of history — original documents and objects which were created at the time under study. They are different from secondary sources, accounts or interpretations of events created by someone without firsthand experience."
A primary source is most often created during the time the events you are studying occurred, such as newspaper articles from the period, correspondence, diplomatic records, original research reports and notes, diaries etc. They may also include items created after the events occurred, but that recount them such as autobiographies and oral histories.
Secondary Sources are accounts written after the fact with the benefit of hindsight. They are interpretations and evaluations of primary sources. Secondary sources are not evidence, but rather commentary on and discussion of evidence.¹
A tertiary source presents summaries or condensed versions of materials, usually with references back to the primary and/or secondary sources.