In Drupal 8, the entire block system got an overhaul, and there are lots of goodies in there. I took a tour of the new system with a short video. Some of the biggest changes to see are that you can now use blocks more than once on your site, and there is a new Custom block library that lets you create block types, which are very much like content types for blocks. They let you add fields to blocks, and give you more fine-grained control over how those fields are displayed depending on the location. Check out the video to see some of this in action.