Hello Backloggers,
Did you know that Milestones & Versions are available across every plan in Backlog?
Some of you may raise the question why milestones and versions share the same form section in the project settings page.
We hear you and would like to share why and how the two features work in Backlog.
Milestones / Versions in Backlog
Milestones act as a forecast timeline which helps you and your team focus on the major progress of the project or tasks that you want to achieve.
Once you have achieved a milestone, it will be released. The “released milestone” then acts as a Version in Backlog. This helps you keep track of the changes that you have made for the “released milestone”.
How does it work?
As above, major tasks have been broken down into smaller parts and the deliverable plan has been forecast with 3 milestones - 1.0, 2.0 & 3.0.
Once members have completed the PH 1 tasks, Milestone 1.0 is achieved and ready to be released. After releasing 1.0, members will continue to work towards Milestone 2.0.
When there are changes or improvements to be made for the first release - 1.0 within Milestone 2.0 progress stage, a new task can be added.
While changes or improvements are occurring in the current Milestone, they are related to the first released version (Version 1.0), therefore the task attributes are added as Milestone: 2.0 & Version: 1.0.
We hope this sharing helps you, and do share with us how you are utilizing milestones and versions in your projects. 
Happy Collaborating!