According to the Project Management Institute, a milestone is the planned completion of a significant event in the project. Every project should have 4-5 milestones.
In a Smartsheet project plan, marking the “Duration” column as 0 (zero) days creates a milestone.
As shown in the screenshot below, a task that has been designated as a milestone highlights the entire row in light blue a pale color and is marked on the Gantt chart with a diamond.
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