A work breakown structure or WBS is a fundamental tool commonly used in project management and systems engineering. It is a tree-like structure that permits summing of subordinate costs for tasks, materials, etc., into their successively higher level “parent” tasks, materials, etc. For each element of the work breakdown structure, a description of the task to be performed is generated. This technique (sometimes called a System Breakdown Structure ) is used to define and organize the total scope of a project.