All research can be roughly divided into primary and secondary categories. Understanding the difference between primary and secondary research and sources is crucial when using or referring to historical and scientific documents. While this understanding is perhaps most important in a formal academic context, an understanding of this topic allows any reader to better scrutinise any material.
What constitutes primary research differs according to the field you are studying, but the definition of secondary research remains the same. Secondary research--often published in academic books and journals--consists of analysing information that has originally been presented in a primary source.
In the Humanities
In humanities topics such as history and philosophy, primary research is defined as the study of anything that was created during or soon after a historical event occurred. In some fields, such as classical history, the definition of a primary source is much more loose, because in many cases no exact contemporary sources are available. Thus, writers who reported the works of earlier lost sources are often regarded as primary source material. Examples of primary sources in the humanities include newspaper articles, memoirs and fine art.
In the Natural Sciences
In the natural sciences, such as physics and chemistry, primary research is the study of original findings derived from either the experiments or theories of other scientists. This research--including lab and field reports--is found almost exclusively in academic journals.
In the Social Sciences
The definition of primary research is slightly different in the social sciences. While all the same criteria that apply to primary research in the humanities apply to the social sciences, a new category--numerical data derived from experimentation--is also considered primary research for social scientists, including statistical data and surveys.
Primary and secondary research are interwoven, and many sources provide a rich mix of both. Another form of research, tertiary, provides a summation of the key primary and secondary sources on a topic, so as to make it accessible to a reader who is new to the subject. According to the University of Maryland Libraries website, this form of research is generally considered inadmissible in academic papers, as it lacks the nuance and depth of primary and secondary sources.