Review articles can help you start your research. Because they provide an overview or summary of significant research in a particular subject area, they are useful as introductions to a new area or as updates to a more familiar one. Authors of review articles write an organized account of current work after having read widely in the literature on the subject. Some of the characteristics and uses of review articles are listed below.

Review articles

• do not report original research (are not part of the primary literature)
• review previously published literature on a particular topic
• report on work done by many researchers
• frequently focus on a specific time period
• are long articles, typically 20 - 60 pages
• usually contain extensive lists of literature references

From review articles you may learn about

• major research questions of current interest
• who is actively working and publishing in the field
• significant recent developments in the field
• open questions that need further research
• current techniques and methodologies
• terminology you can use in database searches to find more articles
• references to the original research reports

Tips on Finding Review Articles using PubMed are located under the PubMed tab.

Review articles are only one of many types of documents in the scientific literature, each serving a particular purpose. Much original scientific research is published as research articles or research communications in journals. These first-hand accounts by those who did the research are part of the primary literature.

Research articles (journal articles)

• give a full report on new research conducted by the authors
• are of intermediate length, typically 5 - 30 pages
• are usually divided into sections such as introduction, methods, results, discussion, and conclusion
• provide sufficient detail for others to evaluate the conclusions or repeat the experiment
• cite relevant literature used by the authors in their research
• may have associated supplementary material or research data available

Communications (journal articles) - sometimes labeled as a letter or note

• report a significant research result that can stand alone or may not require an extensive study
• are brief, typically 2 - 4 pages
• are usually not divided into sections
• cite relevant literature used by the authors in their research
• should not be confused with letters to the editor

Other common types of documents that may turn up in database searches include:

Conference proceedings

• report on presentations made at professional meetings
• may be full articles or just abstracts of presentations

Patents

• describe a new invention
• provide legal rights for the inventor
• are government documents

Dissertations

• describe new research conducted for a Ph.D. or other advanced degree
• are reviewed and accepted by a faculty committee

In the sciences "primary literature" refers to first-hand accounts of new research written by those who conducted the research.

While patents, dissertations, and other documents report original research, journal articles are probably the most widely used primary sources in the sciences.

To recognize primary literature, consider the following:

• Do the authors write about studies or experiments they conducted?
• Are details of experimental procedures or methods described?
• Are experimental results reported?