Series fiction is a set of books, typically written by the same author, that contain similar themes, settings, or characters in each new addition. Book series can range in length from three books to over 50 books per series. The majority of series fiction falls into children or young adult categories or in genres such as fantasy, science fiction, or mystery.
Although most book series come numbered, not all books will need to be read chronologically. Some series do not keep the same characters or settings in each book, but they will retain similar plot lines and story characteristics. R.L. Stine's horror series Fear Street and Goosebumps introduce new characters in each book, but the novels all contain similar scary themes and story structure.
Some series fiction will feature the same characters in each book while rarely referencing past stories or events. Mystery series such as Nancy Drew or the Box Car Children can be read and enjoyed out of order without confusion, with only a few stories overlapping. These novels are often written assuming the reader has no prior knowledge of the series, and the authors make an effort to reintroduce the main characters and setting in each new installment.
Many book series contain ongoing stories that are understood best when read straight through from the beginning. Although each book may have its own focus and story arc, an overlying story arc is also being crafted over the entire series. Books such as Harry Potter or Lord of the Rings were written with the expectation that the reader would go through each book in the intended order.
Not all book series will follow chronological order when published, however. Some authors skip around on their timeline, gradually revealing past and future events in the order they choose. C.S. Lewis uses this approach in The Chronicles of Narnia.
Books written for upper elementary students are often organized into series. Popular examples include The Diary of a Wimpy Kid, The Adventures of Captain Underpants, and Pendragon. Series fiction for kids is sometimes cited as an effective method of enticing students to read. As children grow attached to their favorite characters, they will usually want to keep buying each new book to find out what happens next. Young adult novels are sometimes written as series fiction, especially when looking at teen books about supernatural characters such as witches, vampires, or fairies. High school drama novels like Gossip Girl or Pretty Little Liars also frequently fall into the series fiction category.
Although general adult fiction tends to produce more stand-alone books, many fantasy and science fiction novels are series fiction. Mystery series usually follow around the same detective from book to book, but these books tend to keep each story arc within one novel. Historical fiction also features several book series; these series might trade out main characters as the series continues, but the stories typically remain set in the same country and era.