In a series, every book shares one worldbuilding library. You create a character once and use it in Book 1, Book 2 and beyond, and versions track how the character changes across the whole series, not just one book.
Standalone books and series
A standalone book has its own worldbuilding, used only by that book.
A series has one shared library. Open Worldbuilding from the series or from any book in it and you'll see the same elements. A change you make in one book shows up in all of them. The AI writing tools in the editor and the worldbuilding nodes in each book's Story Planner use the series' library too.
To set up a series, see Creating a New Series.
Opening the series' worldbuilding
On the Series Hub, click the Series Lore Portal card. It opens Worldbuilding for the whole series.
You can also open Worldbuilding in the sidebar while working on any book in the series. It's the same library either way.
Book numbers in versions
Every version of an element says when it starts applying: a Book Number and a Chapter Number (when you create an element, the same pair is called Effective Book and Effective Chapter).
In a series, the book number is the book's place in the series: the number shown as Book 1, Book 2 and so on on the Series Hub.
Versions are ordered by book first, then chapter. So a version at Book 2, Chapter 1 comes after every version in Book 1, however many chapters Book 1 has.
While you write Book 2, the Notes Panel shows each element as it stands at your current chapter of Book 2. Versions from Book 1 still apply until a Book 2 version replaces them, and versions for Book 3 stay hidden.
Example: Master Ignatius has a Baseline at Book 1, Chapter 0 and a new version at Book 2, Chapter 5. In Book 1 and in Book 2 Chapters 1 to 4 you see the Baseline. From Book 2, Chapter 5 onward you see the new version.
In a standalone book, leave the book number at 1.
For the basics of versions, see Worldbuilding Versioning.
Seeing the whole series
The Relationship Map covers the whole series. Use its Book and Chapter filters to see how relationships stand at any point, in any book.
Moving books into and out of a series
Adding an existing book to a series: the book's worldbuilding moves into the series' library, so every book in the series can use it. Its pins, planner links and relationships come along.
Taking a book out of a series: the series keeps its worldbuilding, so the book leaves with none of its own. The exception is the series' only book, which can take the series' worldbuilding with it.
Deleting a series but keeping its books: tick Copy series worldbuilding elements to each standalone book (it's ticked by default). Each book gets its own copy of the library, with all cards and versions. Only the series' owner can do this.
For the steps, see "Moving a book into or out of a series" in Creating a New Series.
Plans
On the Free plan, the limit of 5 elements and 10 versions counts everything across all your books and series, except the example project. When a deleted series' library is copied into several books, the extra copies count too. Paid plans have no limit.
Tips
Create elements in the series rather than repeating them in each book. One element with versions is easier to keep consistent than several copies.
When a character changes between books, add a version at the new book's chapter where the change happens, rather than editing the Baseline.
Have your world in another app? Use Import worldbuilding on the Series Hub to bring it into the series' shared library. See Importing Worldbuilding from Campfire.