This document provides an introduction to the topic of ecological equilibrium. It defines key terms like ecosystem, biotic and abiotic factors, habitat, niche, and ecology. It discusses the main divisions of ecology and objectives of studying ecology, which include understanding dynamics of surroundings and conserving the environment. The three pillars of sustainability - economic, social, and environmental development - are explained. The concepts of ecological balance, balance of nature, and ecosystem stability are introduced. Finally, issues affecting ecological equilibrium like climatic, topographic, edaphic, biotic factors and limiting factors are outlined.