In recent decades, sustainability has gained prominence as a key concern, attracting increasinging interest from researchers, business leaders, and policymakeworldwide This chapter provides a comprehensive study of the foundations of sustainability, a concept that, while long a cornerstone of developers’ discourse and a vital criterion for the practical thinking and intervention of development actors, has always been dynamically interpreted and evolving. The chapter begins by reviewing relevant literature to explore the concept of sustainability and traces its roots through the history of sustainability. A significant portion is dedicated to integrating sustainability and development, introducing sustainable development and its three interconnected dimensions: environmental sustainability, economic sustainability, and social sustainability. Furthermore, it clarifies the critical roles of institutions, technology, and innovation in fostering sustainability, as well as the importance of multi-level governance in achieving sustainable development goals. The discussion then moves to methods for sustainability assessment and addresses global sustainability challenges. Finally, the chapter addresses sustainability in Iran explicitly, outlining key initiatives and primary concerns in this context. This chapter provides an essential framework for understanding the complexities and requirements of sustainability in the contemporary world.