What belongs solely to the Development Team?

The Sprint Backlog is an artifact that belongs solely to the Development Team because it consists of the items from the Product Backlog that the team has selected to complete during the current Sprint, along with a plan for delivering the increment of work. This means that the Development Team has full ownership over the Sprint Backlog, as they are solely responsible for determining how much work they can commit to complete within the Sprint and how they will accomplish that work.

While the Product Backlog is managed by the Product Owner and reflects the overall priorities and requirements of the product, and the Definition of Done is a commonly understood standard across the team but may not be exclusive to just the Development Team, the Sprint Goal, although it provides direction for the whole Scrum Team, is still something that is defined collaboratively. Therefore, those items are not solely under the Development Team's purview.

The Sprint Backlog, on the other hand, is entirely shaped and owned by the Development Team. They create and adapt it as needed throughout the Sprint, reflecting their understanding of the work required to meet the Sprint Goal. This ownership ensures that the Development Team can work effectively and hold themselves accountable for their commitments.