Primary literature in the field of science refers to original reports of research reviewed by experts and published in scholarly journals (periodical publications in which scholarship relating to a particular academic discipline is published). In general, primary literature in the sciences is written in a formulaic manner including the following sections: abstract, introduction, materials and methods, results, discussion, acknowledgements, references. Primary literature is what we are searching for when we need "journal articles" for class assignments.
Primary literature is sometimes referred to as "peer reviewed" because it undergoes a formal review process prior to publication.
Learn more about peer review by watching this short (3 minute) video by North Carolina State University:
As you search for primary literature you will encounter many different types of publications. Explore the definitions below to familiarize yourself with the different types of literature commonly encountered during a search for scientific information.
Peer-reviewed (or refereed): Articles that have undergone the peer review process. This can include empirical studies, review articles, meta-analyses etc.
Empirical study (or primary article): An empirical study is one that seeks to gain new knowledge through direct or indirect observation and research. Publications of empirical studies are reports of original research and said research's findings. Generally in the sciences empirical articles have the following layout referred to as the "IMRaD" format: Introduction, Methods, Results, and Discussion.
Review article: A review article provides a synthesis of existing research on a particular topic. They are not reports of original research. Review Articles are excellent resources for discovering what the key articles are for a given topic.
Systematic review: Systematic reviews are methodical reviews and analyzes of literature pertinent to a specific research question. Systematic reviews aim to identify and synthesize all of the primary research related to a question in an unbiased, reproducible way to provide evidence for practice and decision-making.
Meta-analysis: Meta-analysis combine data from disparate independent studies into a new analysis using a variety of statistical methods and procedures. The aim of a meta-analysis is to combine disparate data sets to draw a conclusion with greater statistical power than that of the individual studies.
Grey Literature: Grey Literature refers to any literature-papers, reports, technical notes, etc.-not published or distributed in the traditional manner (i.e. via commercial publishers). It can be difficult to locate because it may not be indexed and is not widely distributed.
Commentary (editorials): Articles expressing a authors view about a particular issue are often published in academic journals as commentary, editorial, opinion or perspective pieces. Some commentary pieces are thoroughly researched, citing peer reviewed literature. While other pieces are basic orations of an individual's perspective and do not reference additional sources. Commentary articles often appear in peer-reviewed journals but are not empirical studies.