If you are just starting with Drupal 8 then one of the most important things you should know is to enable the debug mode and error reporting on Drupal 8. This is really important for backend as well as frontend developer to the full error on your screen while you are working because you might not know what is the exact issue with the site with just a generic error statement.
A Progressive Web App (PWA) is a web app that uses modern web capabilities to deliver an app-like experience to users by combining features offered by most modern browsers with the benefits of mobile experience. Integration of PWA with Drupal makes Drupal inherit the latest web technologies and harness devices capabilities.
While working on Drupal 8 one of the issues you might face is you won't get "Register" link for anonymous user. Here are two simple ways on how to hide "Register" link for users with administrator role.