A frequent question I get from customers at the bookstore is whether a particular book series needs to be read in order. Depending on the series in question, I’ll usually respond with a) Yes, each installment builds on the previous one and it would be difficult to follow if read out of order; or b) You can read them in any order and not miss anything, like Nancy Drew (a reference that always clicks with parents and grandparents); or c) Well, each book has a stand-alone plot with a beginning and end, but there’s also an overarching background plot that builds throughout the series. And, then again, there are some series that defy any of those broad categories. I began wondering recently if there are standard publishing terms for the different types of series–some better, more succinct verbiage I could borrow for booktalking and, possibly, for some handy in-store signage.

Perhaps my research skills are lacking, but I haven’t managed to dig up anything definitive. Publishing pros: do you have a shorthand that you use to differentiate the series types?
I did find a great blog post from years ago by author Brandon Sanderson in which he bestows his own names on three major types of series: The Saga, The Serialized Epic, and The Continuing Adventures. Definitely worth a read!
There are readers of all ages who will always want to read a series in the order in which the books were published, regardless of whether it’s necessary to following the story. In that case, it’s always helpful to have those handy numbers on the spines or at least a chronological list of the author’s works in the front matter.
Of course, sometimes there are series that aren’t really series but groups of “companion books.” Or even a series that changes it’s mind about the order in which it should be read, like Chronicles of Narnia. If you’re old enough, you probably remember when The Lion, the Witch, and the Wardrobe was the first book in the series. Some years ago, however, the American editions of the series were renumbered based on the chronology of the events in the story, which is apparently how they had already been published in Britain for decades. There’s an excellent summation of this called “The Narnian Order of Things” on the official C.S. Lewis website.
I’d love to hear your thoughts on what, if anything, you call the different varieties of book series. Seriously!