The document discusses the concepts of resilience and vulnerability in ecological and social systems. It defines resilience as the capacity of a system to withstand shocks while still maintaining its basic functions and structure. Vulnerability refers to the exposure of human populations to shocks due to a loss of resilience. The document advocates applying a resilience lens to development in order to foster systems that can adapt to changes while maintaining desirable functions and states. It provides examples of factors that increase social-ecological resilience, like diversity, knowledge sharing, and self-organization across scales.