The thousands of periodicals in the Auburn University Libraries form a continuum ranging from "popular" magazines through "trade/technical" publications to "scholarly/professional/refereed" journals. It is important to know the difference. The following chart lists the typical characteristics of these three kinds of periodicals. Evaluating a periodical by these criteria should allow for the choice of appropriate sources for various types of assignments. Keep in mind, however, that some periodicals defy easy categories.