An ecosystem is a community or group of living organisms (such as plants, animals, and microorganisms) that live and interact with each other within a specific physical environment. This environment also includes non-living components like sunlight, water, soil, air, temperature, and nutrients. These living (biotic) and non-living (abiotic) components are interconnected through processes like nutrient cycles and energy flows. Ecosystems can vary greatly in size—from very small ones like a pond or a puddle, to very large ones like a rainforest or even the entire Earth. The living organisms within an ecosystem have distinct roles such as producers (plants that make their own food through photosynthesis), consumers (animals that eat plants or other animals), and decomposers (organisms that break down dead matter). Overall, an ecosystem is a functional unit consisting of living organisms and their physical environment interacting as a system, where energy flows and matter cycles sustain life and ecological balance. Ecosystems are crucial for the health of the planet as they form the foundation for the biosphere and help maintain environmental stability. This definition covers the ecological, biological, and environmental aspects that explain what an ecosystem is and how it functions.