This document provides context and definitions for the concept of sustainable development. It discusses how sustainable development has become a widely used but ambiguous concept that different groups can interpret in various ways. The document traces the history and antecedents of sustainable development, from concerns around peace, freedom, development and the environment after World War 2. It summarizes the key reports and conferences that helped establish and spread the concept, including the Brundtland Commission report in 1987. The document examines different definitions of sustainable development, particularly focusing on what aspects are meant to be sustained (nature, life support systems, communities) and developed (people, economy, society) in the long-term.