Circular economy principles offer a framework for rethinking production and consumption, emphasizing the design of materials and products for longevity and the recovery of resources at their end of use. At the systems level, concepts such as closed-loop production and industrial ecology enable the redesign of material flows. Historically, businesses and policy-makers have recognized the extensive environmental shortcomings and social inequality associated with meeting the needs of approximately eight billion people through production and consumption patterns that dissipate resources rapidly. These consequences are an inherent aspect of the prevailing linear economic model, which provides societies with affordable goods but little room for error as resource constraints begin to bind. Circular economy is a broad set of principles that strive to design out waste and pollution, keep products and materials in use, and regenerate natural systems. By closing the loops of both material and energetic flows, the approach seeks to reduce pressure on the natural environment and minimize the resulting emissions and waste. Historically, the primary benefit of closing materials loops has been the buffering of the economy against external supply shocks. In recent decades, however, globalization has shifted environmental and social concerns to the forefront. Closing loops not only reduces dependence on volatile materials markets, such as those for oil and metals, but also mitigates environmental and social impacts linked to resource extraction in other parts of the world. The traditional economy resembles a circle primarily because of the currency cycle: all agents buy and sell goods and services endlessly in exchange for money. Physically, this morphs into a linear materials and energy economy. Raw materials are extracted and processed into semi-manufactured and finished goods, which are then used and disposed of as waste. The circular economy concept aims to close the materials and natural capital loops. Feedback loops can either be inner loops—such as reuse, repair, and remanufacturing—or outer loops, which recover useful materials through recycling. Adopting a life cycle perspective minimizes resource use, pollution, and carbon emissions at each stage of a product's life cycle. Society functions as an interrelated system.