Tutorial Step 3: Create Milestones
Milestones are a project's important moments. They don't take up time like tasks do; they just mark certain points in the project cycle.
In task view 
, use the action menu 
to add a milestone, or just use the Task Information inspector 
to change an existing task's Type to Milestone.
, use the action menu to add a milestone, or just use the Task Information inspector to change an existing task's Type to Milestone. 
The milestone appears as a diamond on the Gantt chart. In this example, the milestone represents the completion of a model airplane.