A Bill of Materials (BOM) in construction is a document that lists all the materials, parts, and subassemblies needed to construct a project. It also provides the required quantities for each item and describes how they are to be used during the construction process. The BOM covers everything from large items like steel beams and columns to small parts like screws and nails. By providing detailed information about the pieces needed for a job, it ensures that no part is left out and that sufficient materials are available before breaking ground on any project.