A procurement document is a document that is used to solicit proposals or quotations from potential suppliers or vendors of products or services for a project. A procurement document describes the problem or need, the desired solution, the evaluation criteria, and the contractual terms and conditions. A procurement document can be a request for proposal (RFP), a request for quote (RFQ), a request for information (RFI), or an invitation for bid (IFB). An invitation for bid (IFB) is a type of procurement document that is used to request bids from prospective sellers of products or services. An IFB describes the specifications, quantity, quality, and delivery schedule of the products or services. An IFB invites sellers to submit a sealed bid that indicates the cost of providing the products or services. An IFB is used when the buyer has a well-defined or standard problem or need, and wants to select the lowest bidder among the qualified sellers123. A project work breakdown structure (WBS) is not a procurement document, but a project management document. A WBS is a hierarchical decomposition of the project scope into smaller and manageable components. A WBS defines the deliverables, activities, and tasks that are required to complete the project4. A project charter is not a procurement document, but a project management document. A project charter is a document that formally authorizes the initiation of a project. A project charter defines the purpose, objectives, scope, assumptions, constraints, risks, stakeholders, roles, responsibilities, and authority of the project. A vision document is not a procurement document, but a business analysis document. A vision document is a document that describes the desired future state of a solution. A vision document defines the goals, benefits, features, and scope of the solution. References: CBAP® Handbook, CBAP® Exam Prep Study Guide, Project Management Institute, Project Work Breakdown Structure, [Project Charter], [Vision Document]