Initial requirements modeling
At the beginning of a project there is a need to envision the high-level requirements and to understand the scope of the release (what the system should do) to define the boundaries of the effort. The goal is to get a gut feel for what the project is all about.
During this phase requirements and solutions evolve through the collaborative effort of self-organising cross-functional teams and their customers/end users. It advocates adaptive planning, evolutionary development, early delivery, and continuous improvement, and it encourages rapid and flexible response to change.