The rapidly expanding and evolving landscape of data production and sharing is an opportunity for National Statistical Offices (NSOs) to exercise expertise in the larger statistical as well as national data community. NSOs must expand their role into data stewardship to fully carry out their mandate. As the transformation is multifaceted, there are different interpretations of how the NSO role can and should change, and what data stewardship means in this context. This work focuses on defining and explaining the foundational concepts and frameworks relevant to data stewardship. It aims to serve as a guide to statistical offices regardless of data or structural maturity. It will help offices decide whether they should extend their role as government data stewards, as well as provide inspiration and ideas to those who are already performing this function.