Victor Watson defined series fiction broadly as "a sequence of related stories about the same groups of characters, usually by the same author", as well as "a series of narratives, published separately, often over a considerable period of time, mostly about the same characters, and usually written by one author". He notes that its key characteristics that distinguish it from other types of fiction is its "extended overall length and its composition in separate narratives". Watson although noted that there are notable exceptions to his definition. While the unifying feature for most series are characters, for some, that can be a concept, a place or an institution. For example, the
Greyfriars School series by
Charles Hamilton, the
Chalet School series by
Elinor Brent-Dyer or the
Green Knowe series by
Lucy Boston feature changing characters, and are connected through a particular place; while
Lucy Fitch Perkins's
Twins series had a theme of featuring twins, with characters, countries and historical periods varying between the installments. Other reasons for continuing the series have been described as the author's desire to "fill in narrative gaps" or to write "major ideological reappraisals". Such communities, particularly in the Internet era, can also lead to increased interaction between readers and writers, influencing the course of the series in line with fan's wishes as expressed online. Shortest series can be as short as a single
trilogy. Larger series can number as many as several hundred installments, particularly in cases of
larger franchises and
shared universes, such as, for example,
Star Trek and
Star Wars science fiction series, or the
Longarm westerns. Other terms related to series fiction, sometimes used as
synonyms, include, among others, multi-part novels, sequences, and sagas. Also related are the concepts of shared universes,
fan fiction and
canon, particularly common in
speculative fiction series (science fiction, fantasy and horror). == Reception ==