Leanpub authors can publish updates to their books or courses any time.

Sometimes they update their books without notifying readers about it, because they've just fixed a few typos or made minor improvements.

When authors make more substantial updates, like adding new chapters, they will typically send notifications to readers who have signed up for update notifications:

http://help.leanpub.com/en/articles/3892064-leanpub-books-can-be-updated-with-new-content-any-time-what-can-i-do-to-get-notified-when-a-leanpub-author-publishes-a-new-version-of-their-book-or-course

These notifications will typically include detailed descriptions of the updates the author has made to the latest version of their book or course.

It's up to each individual author to decide how they want to communicate with their readers about the details of book or course updates.

Some authors may explain all their changes in a "changelog" section at the beginning or end of their book.

To see if a book has a changelog, or a description of changes or updates, the best thing to do is to just download the latest version of the book from your library here:

https://leanpub.com/user_dashboard/library

You can also contact the author to ask them about the details of any updates. Typically Leanpub authors love hearing from their readers about things like this!

Here are the instructions for contacting a Leanpub author:

http://help.leanpub.com/en/articles/3852119-how-can-i-contact-a-leanpub-author

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Interested in creating your first Leanpub book? Here are some quick tutorials for our most popular writing modes: http://help.leanpub.com/en/articles/3088382-quick-walkthroughs-for-getting-started-on-a-leanpub-book