Milestones are a way that you can set dates that tasks have to be completed by.
These could be used for ensuring that a Sprint (cycle of agile) is to be completed by. When a version has to be delivered to the client or when there are other important deadlines that must be met.
Click on the Milestones tab
Initially there are no milestones.
Enter the details of the milestone and click create.
You will now see a diamond on the date you set the milestone for.
If you click on the milestone you will open up its details
Click + to add a new card to this milestone.
This is saying that this card needs to be completed by this milestone date.
To add an existing card to the milestone open the card.
Then open the properties
Click on the milestone to add it to the card
You will now see a diamond in the corner of the card, this shows it has a milestone attached.
In the milestone timeline we can now see the cards attached to each milestone
To edit a milestone date click the edit pencil below the timeline.