An ecosystem is a community of living organisms interacting with their physical environment in a specific area. It consists of biotic factors (plants, animals, and microorganisms) and abiotic factors (sunlight, air, water, soil, and climate). Ecosystems function through energy flow, nutrient cycling, and ecological interactions such as predation, competition, and symbiosis. Energy flows through the ecosystem via food chains and food webs, while nutrients are recycled through biogeochemical cycles. Understanding ecosystems is crucial for maintaining biodiversity and ecological stability.