The "Rebound Effect" refers to the phenomenon where improvements in energy efficiency lead to an increase in energy consumption. For example, when a household buys a more efficient appliance, it may use the savings from lower energy bills to purchase additional devices or use the appliance more frequently, ultimately offsetting the expected energy savings. This effect can also occur on a larger scale, such as when a country invests in renewable energy sources. While these sources reduce reliance on fossil fuels, the lower costs of energy can encourage increased consumption, potentially negating some of the environmental benefits gained from the initial efficiency improvements.