A BOM, or bill of materials, is a list of the raw materials, sub-assemblies, intermediate assemblies, and other components that are required to manufacture a finished product. It typically includes information such as the quantity of each component needed, the unit of measure, and the part number or reference designator. A BOM can be represented in a variety of formats, such as a list, table, or hierarchical structure, and it can be used for a variety of purposes, such as planning, scheduling, procurement, and quality control. In a manufacturing or production environment, the BOM is often considered to be a critical component of the product definition, and it is typically managed using specialized software tools, such as a product lifecycle management (PLM) system.