What Is the WBS?
The WBS is a hierarchical decomposition of all the activities the project team must complete. The WBS defines the total scope of the project and provides the basis upon which work can be scheduled.
Each level of the decomposition increases the detailed view of the tasks to be completed to create work products. Verbs are used to describe each activity. The hierarchy has as many levels as required to define the work. The number of levels usually varies from one major element to another. The WBS focuses on how to produce the work products that are defined in the PBS, which focuses on what to produce.
This figure illustrates two ways to show the same WBS decomposition. One is a tree diagram, and the other is an indented list or outline.