Scientific literature is divided into two basic categories - "primary" and "secondary".
Primary
With primary literature the author (or author group) are performing their own research. They are describing their own research, usually in the form of a journal article. Hallmarks of primary sources are ones that include sections such as an introduction, literature review, methodology, results, discussion, and conclusions, along with a bibliography. Not all primary literature would include all of these sections explicitly named, but these are the most common.
Beware that review articles, where an author is summarizing and synthesizing the work of others, is not considered primary, even if it contains all the sections described above. Review articles are part of the secondary scientific literature.
Secondary
A secondary source interprets and analyzes primary sources. These sources are one or more steps removed from the scientific experiment. Review articles are always considered secondary sources. Some types of secondary sources include:
The information on this page is reused with permission from a Research Guide written by the Loyola University Chicago Reference Department.