According to Scrum, the translation of the vision into a finished product is not done by preparing detailed lists of requirements. Instead, requirements are phrased in the form of clear characteristics from the user’s point of view (see User Stories). The list of these requirements is the product backlog. The requirements are implemented gradually and iteratively in two- to four-week phases, known as sprints. In Scrum, at the end of each sprint a finished subproduct is delivered, which should be in a condition in which it could be delivered to the customer (potentially shippable product). Following this cycle, the product, requirements and approach are reviewed and further developed in the next sprint.
The Scrum framework counteracts the complexity of development projects, in which it is difficult to create a comprehensive plan due to unclear requirements and solution approaches at the very beginning. Scrum does not reduce the complexity of the task, but rather structures it into smaller and less complex pieces and iteratively creates intermediate deliverables. These concrete interim results are used to efficiently clarify the missing requirements and solution techniques. In addition to the product, the planning in Scrum is also developed iteratively. This puts the focus of the project planning on the essentials and enables a high level of discipline when it comes to planning.