A Hierarchy that results from breaking down or ordering the project so that the activities on any level are a subsection of the level of detail shown above.

A hierarchical and logically oriented grouping of project elements (typically deliverable or phase based) that defines the total scope of the project and organizes it in a manner that is consistent with the execution plan. The top level of the WBS consists of a single element that reflects the entire project scope. Each subsequent level represents an increased level of detail.