If we are talking about internet addresses encoded in QR codes (URL), Static QR codes are containing final destination where you will be redirected after scanning. Dynamic QR codes contain intermediate location that willl then redirect user to desired des

It allows you to manage multiple versions of your Joomla articles and go back to in case there have been edits that were not supposed to be made or maybe you just want to go back and see.

Joomla team is working hard to release its Joomla 4 and it's expected that they will release the version at the end of 2018 or at the beginning of 2019..