A periodical is any publication that is published multiple times (periodically). Periodicals include materials such as popular magazines, scholarly journals, and newspapers.
It is important to understand the difference between a popular periodical and a scholarly one. When you are doing research, most of your sources should be scholarly.
Often, popular periodicals are called magazines and scholarly periodicals are called journals. Many times it will be acceptable to use some popular material, but research papers should not be based solely on popular literature.
Scholarly sources are in-depth accounts of original research. Scholarly sources are written by experts in a particular field or discipline, and their primary intended audience is other experts in that particular field and students of that discipline. They are written for the purpose of scholarly communication; to report findings and advance research. The language used often includes specialized terminology. Importantly, authors of scholarly sources are required to provide properly-formatted references or citations for the information in their papers. Scholarly sources go through a peer-review process where other experts in the field look at the content, format, and style of the paper before publication.
Scholarly sources include journals such as Journal of the American Medical Association, Journal of Data Information and Management, and American Journal of Psychiatry.
Peer review is the rigorous process through which the validity and quality of a scholarly article are determined before publication in scientific, academic, or professional journals.
Peer review maintains the integrity of scientific research by stopping the publication of invalid or poor quality work. Scholarly sources go through the peer review process and popular sources do not, but that is not the only difference between popular and scholarly sources.
The peer-review process is also sometimes called "refereeing," so a peer-reviewed journal might also be called a "refereed journal."
CAUTION: Not every article in a peer-reviewed journal is peer-reviewed. Scholarly journals also contain articles like book reviews, opinion pieces, introductory articles, editorials, etc. that have not gone through the peer-review process. If you must use scholarly, peer-reviewed sources for a project or paper, you need to look at the article yourself to determine if it is one of the peer-reviewed, scholarly articles published in the journal or not.
Watch the videos below, created by the librarians at North Carolina State University, for an overview of the peer-review process and how scholarly articles make their way from researcher to publication to library.
Trade sources, such as trade journals or trade magazines, are periodicals that publish articles relevant to a particular field or industry. They are usually written by professionals actively working in the field, or by journalists who have knowledge of the field. A trade source's primary intended audience is working professionals. Trade sources often have advertisements that are targeted to the professionals in that industry, highlighting specific tools or products that would be used in their work. Trade sources may sometimes include references or citations, but they are generally not required.
Trade sources include journals and magazines such as American Libraries, Trade Finance, and GPS World:
Popular sources are secondary discussions of original work or events, and may include opinions. Popular sources are written by journalists for the purpose of entertaining or informing the general public. The language used is easily understandable for most people. Popular sources are not required to provide references or information about source material. Popular sources are reviewed by editorial staff for format and style.
Popular sources include magazines and newspapers such as Time Magazine, The Washington Post and Psychology Today: