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. To make adjustments to your milestone, use the Milestones section of the Project inspector.
, use the action menu to add a milestone. To make adjustments to your milestone, use the Milestones section of the Project inspector. 
The milestone appears as a diamond on the Gantt chart. In this example, the milestone represents the completion of a model airplane.