Primary versus Secondary Sources

Primary sources are usually first hand accounts or experiences, thus the author's account of an event such as a war, the writing of a poem, the collection of data or information by a researcher for empirical research, or a visual artist commenting via their work. For example, RG10 files, found in the Canadiana Héritage database, refers to historical records created by the Department of Indian Affairs and Northern Development and its predecessors, held at Library and Archives Canada (LAC). Record Group 10 includes files, correspondence and transcripts on all aspects of administration in Canada for both headquarters and field offices. These records are primary sources of original, unpublished material.

Other examples where first hand accounts may be found:

• Newspaper accounts written by reporters and/or included quotes by those who witnessed the event
• Diaries: be wary of edited diaries in which editors may have obscured the whole story by leaving parts out, such as Queen Victoria's diaries or the Diary of a Young Girl by Anne Frank.
• Speeches, letters, interviews, poetry, music
• Legislation and regulation, treaties
• Data sets and survey data
• Photographs, video, or audio that recorded an event
• Original research: empirical studies such as scholarly research in the form of case studies, dissertations, clinical reports and research articles

Are not primary sources and thus not first hand accounts or personal experiences of an event. Authors of these secondary sources may quote, discuss, summarize, analyze or interpret primary sources. This might include an author reinterpreting a war they did not experience through a modern lens, other authors' or artists' works in a review of that person's body of work, or even a meta-analysis of multiple research studies. 
Typical examples include:

• Most books about a topic, textbooks, magazine articles, commentaries, encyclopedia, almanacs, reviews
• Analysis or interpretation of data 
• Scholarly or other articles about a topic, especially by people not directly involved. 
• Documentaries (though they often include photos or video portions that can be considered primary sources)
• Dissertations, if not empirical, are commonly secondary sources of information as they discuss, summarize, analyze and interpret.

Yes, it is possible for some resources to be associated as both primary and secondary resources but where they fall depends on how you plan to use them.

For example, 

• A textbook is usually considered a secondary source because it describes, summarizes and discusses others' discoveries. But if you were doing research on the history of textbooks or even how a topic has been presented over time in textbooks, then textbooks are considered a primary resource.
• Newspaper eyewitness accounts are primary resources but there are many other articles and opinion columns within newspapers that discuss, interpret, summarize and analyze.