Periodical literature (also called a periodical publication or simply a periodical) is a published work that appears in a new edition on a regular schedule. The most familiar example is the magazine, typically published weekly, monthly, or as a quarterly. Newspapers, often published daily or weekly, are, strictly speaking, serials, not periodicals. Other examples of periodicals are newsletters, literary magazines (literary journals), academic journals (including scientific journals), science magazines, and yearbooks.
These examples are typically published and referenced by volume and issue. "Volume" typically refers to the number of years the publication has been circulated, and "Issue" refers to how many times that periodical has been published during that year. For example, the April 2011 publication of a monthly magazine first published in 2002 would be listed as, "Volume 10, Issue 4." Roman numerals are sometimes used in reference to the Volume number.
When citing a work in a periodical, there are standardized formats such as The Chicago Manual of Style. In the latest edition of this style, a work with volume number 17 and issue number 3 may be written as follows:
Periodicals can be classified into two types: popular and scholarly. Popular periodicals are usually magazines (e.g., Ebony and Esquire). Scholarly journals are most commonly found in libraries and databases. Examples are The Journal of Psychology and the Journal of Social Work.