- Introduction to Twenty Seventeen – New WordPress theme just in time for 2017.
- PDF Thumbnail Previews – Shows a preview thumbnail of the PDFs in the media library instead of the generic icon.
- Video Headers allows videos to play automatically, loop by default don’t have a sound. This is shown with the Twenty Seventeen theme.
- Adding pages while building nav menus. Instead of leaving the customizer, you can do both by adding pages and then building menus within the customizer. Before you had to leave the customizer to create the pages and then come back to the customizer. Now you can do it all at the same time.
- Edit Shortcuts – New icons show you which parts of the site can be customized when doing a live preview of the site.
- Custom CSS – Allows you to see visual tweaks immediately. You can now add custom CSS to your website and instantly see the changes you desire.
See all the updates: https://codex.wordpress.org/Version_4.7