In publishing and library and information science, the term serial is applied to materials "in any medium issued under the same title in a succession of discrete parts, usually numbered (or dated) and appearing at regular or irregular intervals with no predetermined conclusion."
Periodicals
In contrast to serials in general, a periodical has been defined as "A serial publication with its own distinctive title, containing a mix of articles ... by more than one contributor, issued ... at regular stated intervals of less than a year, without prior decision as to when the final issue will appear." Thus a periodical does not admit irregularly spaced publication times. This includes magazines and journals, but not proceedings; it also does not include newspapers.