• Attributions tool: You can now add attribution and licence information to image files in your Media Library. To make this information display publicly in all formats, check the Media Attributions setting under Theme Options. With this box checked, the information will display at the end of each chapter after your body text and before your footnotes. More information to come. (Thanks to Brad Payne and Alex Paredes at BCcampus for building this feature!)
• TablePress: TablePress makes it much easier to create larger, more complex tables, with more interactive functionality, such as the ability to sort by column. (See TablePress.)
• Improved Book Cloning:
  • When cloning, all of the media files from the original book’s media will also import with the book. Previously, cloned books would only retain images. Now, videos, audio files and other media files will also come over.
  • Internal links in cloned books will now be automatically converted to point to the newly-cloned book. URLs will undergo this action as part of the cloning process, so that manual conversion isn’t necessary.
  • The source comparison tool has been improved so that readers can more easily see the differences between the original source book and a cloned book when the user has enabled source comparison on their cloned webbook. Word counts on source books will now be more accurate too.
• Plugins: Book Administrators now have the ability to activate three different plugins inside their books: H5P, Hypothesis, and WP Quick LaTeX. For more information on these plugins and how to activate them, see the Plugins chapter in the Pressbooks Guide. (Note that this feature has been enabled since August.)
• Cover Generator tool: More information to come.

For more information, see Pressbooks 5.5.0 release notes.