In project management, the resource breakdown structure (RBS) is a hierarchical list of resources related by function and resource type that is used to facilitate planning and controlling of project work. The Resource Breakdown Structure includes, at a minimum, the personnel resources needed for successful completion of a project, and preferably contains all resources on which project funds will be spent, including personnel, tools, machinery, materials, equipment and fees and licenses. Money is not considered a resource in the RBS; only those resources that will cost money are included.
Assignable resources, such as personnel, are typically defined from a functional point of view: "who" is doing the work is identified based on their role within the project, rather than their department or role within the parent companies. In some cases, a geographic division may be preferred. Each descending (lower) level represents an increasingly detailed description of the resource until small enough to be used in conjunction with the work breakdown structure (WBS) to allow the work to be planned, monitored and controlled.