In a Gantt chart, how are milestones displayed?

In a Gantt chart, a milestone represents a significant point or event in the project lifecycle, such as a major deliverable completion or a phase gate. By definition, a milestone itself does not consume time or resources, so it is logically represented as an activity with a zero-day duration.

An activity with a one-day duration implies work is being performed over that day, which contradicts the nature of a milestone as a point in time.

Activity-on-node is a method for drawing project network diagrams, not a way to display milestones specifically within a Gantt chart, and finish-to-finish precedence describes a relationship between tasks, not a milestone itself.

An end-to-end bar graph is used to represent tasks with duration, showing the time span over which work is performed, whereas a milestone marks a discrete point in time.