The Coupling Coefficient is a measure used in physics and engineering to describe the efficiency of energy transfer between two systems, such as in electromagnetic or mechanical systems. It quantifies how well one system can influence another, often represented as a value between 0 and 1. A higher coupling coefficient indicates better energy transfer, while a lower value suggests weaker interaction. In the context of transformers, the coupling coefficient helps determine how effectively electrical energy is transferred between the primary and secondary coils. It is crucial for optimizing performance in various applications, including communication systems and signal processing.