Source : Free On-Line Dictionary of Computing

Work Breakdown Structure
     
         (WBS) A division of a project into tasks and
        subtasks.  The tasks are numbered to indicate their
        relationship to each other.  WBSs are indespensible for
        project planning, particularly when estimating time and
        resource requirements.  Some industries use established work
        breakdown structure systems for billing and reporting
        purposes.
     
        (2001-05-09)