Backdrop is a successor to Drupal 7. Split off from the Drupal code-base, Backdrop has made numerous improvements to the user and site developer experience compared to Drupal 7. Backdrop was developed for small businesses and non-profits, communities with numerous similarities to digital humanities.

Drupal 8 was developed for "enterprise", with corresponding assumptions about the server infrastructure underpinning those sites, and the technical proficiency of the team of IT staff supporting the site. Backdrop, in contrast, provides a friendlier, more supportive community for people building websites, who may not have any knowledge of PHP frameworks or templating engines. It also smooths over many of the minor -- but numerous -- irritations inherent in building a Drupal 7 site. As a result, Backdrop for Humanists (so far) is significantly shorter than Drupal for Humanists, because so many things that you previously had to install and configure are set up in a reasonable way from the moment you install Backdrop! 

As of January 2019, some modules that Drupal for Humanists includes that are still half-baked in Backdrop. The author (Quinn) has gotten involved with Backdrop in hopes of getting it up to the same point of usability for digital humanists as Drupal 7. If you have a question about whether Backdrop would be a good choice for your project, you can email Quinn qad [at] stanford [dot] edu.

Backdrop for Humanists is still under development, though Quinn hopes to finish by the beginning of the summer. If you have any questions about Backdrop and digital humanities, please ask!