Business requirements usually consist of both functional requirementsandnon-functional requirements. The plan for implementingfunctionalrequirements is detailed in thesystemdesign. The plan for implementingnon-functionalrequirements is detailed in thesystemarchitecture.
functional requirementdefines a function of asoftware systemor its component.
A function is described as a set of inputs, the behavior, and outputs. may be calculations, technical details, data manipulation and processing and other specific functionality that definewhata system is supposed to accomplish. Behavioral requirements describing all the cases where the system uses the functional requirements are captured in use cases
non-functional requirementis arequirementthat specifies criteria that can be used to judge the operation of a system. Like security , usability,testability, maintainability, extensibility and scalability
Business requirements are often listed in a Business Requirements Document or BRD. The emphasis in a BRD is on what is required, rather than on how to achieve it, which is usually delegated to a Systems Requirements Specification or Document (SRS or SRD) or other variation such as a Functional Specification Document. While supposedly describing the product, system, or software from an external perspective, such documents often define the product/system/software requirements in the context of a chosen technology (a solution approach or architecture).