“Periodical” is the term given to publications that are published regularly (daily, weekly, monthly, quarterly, etc.) for an extended period of time. For many research assignments, your professors will require that you use articles from scholarly journals instead of popular magazines or trade publications.
Characteristics of Popular Magazines
The audience is the general public, not specialists or scholars.
In printed form (or PDF files) are usually very visual: lots of graphics, color, advertisements. Photos or other graphics may not appear in HTML versions of articles.
Articles are usually fairly short and lacking bibliographies or references.
The author’s name is usually given, but there’s no way to tell what his or her background or affiliation is.
Most popular magazine articles are written by staff writers or freelancers, not subject experts.
Characteristics of Trade Publications
The audience is practitioners in a particular field or occupation, e.g., nurses, teachers, accountants, etc.
Layout and design will often be more like popular magazines than academic journals. Illustrations and advertisements, often in color, are common
In addition to news and “how-to” articles, they will often contain announcements, want ads, and other information of interest to people in the field.
The author’s name is often, though not always given, but there’s no way to tell what his or her background or affiliation is. Many trade publication articles are written by staff writers or freelancers, not subject experts.
Characteristics of Scholarly Journals
Also called academic journals, peer-reviewed journals, or refereed journals.
Include articles written by experts in various fields of study; the intended audience is other experts in the field.The authors’ educational credentials and academic or research affiliations are usually included.
Articles can be quite long and “text-heavy,” and will include specialized vocabulary and footnotes and/or lists of sources (bibliographies).
There are some periodicals which don’t fall clearly into any one category. You will need to use your jest judgment to determine which kind of publication or article you are dealing with. Ultimately, you may need to consult your professor as to whether or not a particular article is acceptable for your project.