CAPM Practice: Demonstrate an understanding of project management planning

A milestone is a significant point or event in a project that has zero duration. It marks the completion of a major deliverable or phase, such as obtaining design approval. Milestones are used to track progress and communicate key achievements to stakeholders.

**Why not A:** A zero-duration item in a schedule is not an error; it is a standard way to represent milestones. Milestones are intentionally set with zero duration to mark significant points in the timeline, so no correction is needed.

**Why not B:** Milestones do not require duration because they represent points in time, not work activities. Assigning a duration to a milestone would change its nature and misrepresent it in the schedule. Not all schedule items require work duration.

**Why not C:** A summary task rolls up the durations of its subordinate activities and typically shows a non-zero duration spanning the work beneath it. A zero-duration item specifically indicates a milestone, not a summary task.