A point on the project schedule at which the project team assesses progress and quality, and reviews deviations in scope and specifications. A project may have many interim milestones for internal use only, which signal a transition within a phase and help divide large projects into workable pieces. External milestones or major milestones typically occur at the end of major phases of work and are associated with the completion of major deliverables. External milestones are the points where the team and customer review work to date and agree to proceed with the project, appear as a task with a duration of zero work units, and are exposed on customer reports.