The Renormalization Group (RG) is a mathematical framework used in physics to study systems with many scales, such as phase transitions in materials. It helps simplify complex problems by systematically "zooming out" to analyze how physical quantities change as one observes the system at different scales. This approach is particularly useful in quantum field theory and statistical mechanics. By applying RG, physicists can identify universal behaviors in systems, meaning that certain properties remain consistent across different materials or conditions. This concept is crucial for understanding phenomena like critical points, where systems undergo significant changes, and it connects various areas of theoretical physics, including quantum mechanics and condensed matter physics.