Primary and secondary sources: what are they and why do I need them?

Primary and secondary sources are the two types materials you will use while undertaking your research project. They are both important and needed for your project. The requirements for whether you use more primary or secondary sources depend on your academic level: undergraduate, postgraduate, professional.

Both types of sources have importance and merits of their own, but they are also immensely different.

What are the main differences between primary and secondary sources?

The one main difference between primary and secondary sources is that primary sources are contemporary.

Primary sources are original and originated from the event they refer to. They are not reviews, analyses, criticisms or critiques of events that occurred. They are not second-hand information. For a more detailed description of what a primary source is, where you can access them, and why you need to use them, see this article about primary sources.

Secondary sources are summaries, critiques, opinions, and analyses. They are written by people who did not witness, or have any direct part to play in the event they are describing. The information they contain is based on primary sources, and is the author’s interpretation of the event/subject they are covering. See this article about secondary sources for further information.

Why do I need to use both primary and secondary sources in my research?

Using both types of sources adds to the merit of your research. By including references to secondary sources you are showing that you have truly engaged with your research topic. You are providing extra information and displaying a well-rounded approach to your topic. You are not relying solely on the work of one person, or one institution, for your analysis to be based upon. You are reading broadly and contextually.

Likewise, including primary source references in your research shows that you are also going back to the roots. You are looking at the event or object as it happened, without being able to teleport through time and space. A primary source is vital because it will enable you to make your own judgement on an event or object. Secondary sources are always biased, in one sense or another, so engaging with the primary source yourself allows you to view the topic objectively.

Primary and secondary sources complement each other - looking at both can give you a deeper understanding of each. A primary source can help you to evaluate a secondary source - you will notice aspects of it which the author dismisses, or washes over in their discussion. Likewise, a secondary source can tell you about current trends in research and analysis, while providing you with a broad overview or summary of an extended period of time, or the works of an artist.

Examples of primary and secondary sources

We have put together a list of examples of primary and secondary sources by field of study. It will help you in identifying if your source is of primary or secondary nature.

Examples of primary and secondary sources by discipline.
Arts/HumanitiesSciences
Primary sourcesPoems, diaries, letters, paintings, government records, maps, interviews (transcribed or recorded), photographs, newspaper articlesResults of experiments, case studies, results of clinical trials, minutes of meetings, proceedings of conferences
Secondary sourcesBiographies, Histories, Reviews, Encyclopaedias, Literary criticismDiscussion of importance, analysis of clinical trial, review of results