Network effects is a phenomenon where the value or utility of a good or service to a user increases as the number of other users of the same good or service increases. As an academic concept, it investigates the dynamics of markets and systems characterized by such interdependence, focusing on how user base size influences adoption patterns, competitive advantage, and market structure. Key characteristics include positive feedback loops and the importance of achieving critical mass, leading to significant implications for strategy, policy, and the understanding of technological diffusion and platform economics.