Business object life cycle: Requirements models are used when gathering requirements, and during systems analysis. Whether we consider eliciting requirements to be a separate activity, or a part of systems analysis, the importance of correct requirements must be a high priority for us. Building accurate models means that we can guarantee the correctness of our requirements. All engineering disciplines use models to develop the products they intend to build. Requirements models are used to discover and clarify the functional and data requirements for software and business systems. Additionally, the requirements models are used as specifications for the designers and builders of the system.