All users (except for collaborators) on all account types can create milestones.
Milestones are tasks that are scheduled for one day and have no duration. Milestones are used as reference points to mark a major event or a branching decision point in a project.
You can convert any existing task into a milestone:
Open the task you want to convert to a milestone in Task view or create a new task.
Click the three-dot menu button in the upper right-hand corner of the task.
Select Convert to milestone.
Alternatively, right-click a task in List view and select Convert to milestone from the menu that appears.
If the converted task has no specified start/end dates, the task is converted into a milestone with the current date as a due date. If the end date was specified it becomes the due date for the milestone.
Another way to convert a task into a milestone from Task view:
Open the task you want to convert to a milestone or create a new task.
Click the schedule date section of the task (if the task is currently scheduled for any dates).
Delete the date in the start date field.
Select the date, which the milestone should be scheduled for, in the end date field.
Milestone tasks are displayed as a diamond symbol on Gantt Chart. To create a milestone:
Navigate to a folder, project, or space where you want to create a milestone.
Switch to Gantt Chart.
Scroll to the bottom of the table on the left-hand side of the view.
Click New task and enter a name for the task.
Press Enter on your keyboard or click anywhere outside the field.
Right-click the row of the task that you want to convert into a milestone.
Select Convert to milestone. Alternatively, you can add the due date for the task without the start date.
The milestone is created and you can add any additional information to it.
To convert existing tasks into milestones right-click them on the timeline, click the three-dot menu, and select Convert to milestone.