A summary task is made up of subtasks and summarizes those subtasks. You can use the Microsoft Project outline feature to create summary tasks. Microsoft Project automatically determines summary task information (duration costs, etc.) by using information from the subtasks. A summary task Start date is the earliest start of its subtasks and the summary task Finish is the finish of its latest subtask. The duration for the summary is the total of the working days between its start and finish dates.

The figure below shows what a summary task looks like in the Task Sheet view.