The Work breakdown structure is used to the complete, hierarchic description of all tasks in a project. The WBS illustrates the relationship between different tasks which are needed to achieve the goal of a project. The overall task is divided in subtasks and work packages to show the functions in more detail and with a focus on a visual description. Furthermore, it displays the functional responsibilities and which and how many resources are needed and how much time is required. (1)
The tasks are divided in smaller tasks and the sub-tasks in work packages. The Work packages are the smallest objects and always on the bottom of the WBS.
The purpose of the breakdown is to get a better understanding of a project or an organization. The smallest objects can be monitored and improved to gain a better efficiency and lower costs. This should also lower the risk of migration tasks and show the required skill and knowledge. This makes the WBS a convenient instrument for the planning of projects or other organizations.
The WBS can be divided in three different ways, depended how the project or organization wants to be viewed.
With the object-orientated view the project or organization is orientated by the hierarchy of the products or the organizational structure of the company. The product is divided by components, modules and piece parts.
The function-orientated structure separates the project with the type of operation in the project or organization. One sub-project for the production, one for the purchasing department and so on. This is relatively easy to manage, because the environment is familiar for the employees.
The phase-orientated segmentation shows the different phases of a project and shows the sequence over time. The phases are separated in subtasks and work packages. The project is mostly structured in phases, if there is a clear separation between the different phases.
Furthermore there are different mixed forms. The importance is that the different structures only exists on different levels. (2)
Mostly the WBS is created at the kick off meeting from the whole team. The goals of the project must match the smart criteria and the important milestones should be set.
The Top-Down approach means that the WBS is created from top to bottom. The project as a whole is viewed first and then the different sub-tasks. At last the work packages are defined based on the sub-tasks.
The Bottom-up approach is the opposite of the Top-down. At first it is checked which work packages are needed to reach the specified goal. After that the sub-tasks are formed out of the work packages and at last the overall package is built of the different sub-tasks. (3)
The project management is in charge for the WBS but is created usually by the whole team. The updates are managed by the persons who are responsible for the specific work package. The results of the wbs (problems, analysis and options for solutions) are discussed by the team.