Work Breakdown Structure (WBS) refers to a portion of a total project management plan that is used by the project management team to organize a project into manageable objectives and create a blueprint by which the steps leading to the completion of a project are obtained.
The Work Breakdown Structure can be thought of like an outline of the project and like an outline, becomes more detailed under the subheadings or work packages. The whole project is defined by the Work Breakdown Structure, with the work packages fitting together at the completion of the project to complete the whole.
The work packages are individual steps or portions of the task that must be completed in order to achieve the project management goal. It allows for several different teams to work simultaneously on seperate components of a project. This outline applies to any project where a good or service must be presented to the client in timely manner. These goods or services are called the deliverables, and can be either internal or external. Other terms that are related are work package, control account, contract work breakdown structure, and project summary work breakdown structure.
This term is defined in the 3rd and the 4th edition of the PMBOK.