Intermolecular interactions shape chemistry and biology, influencing everything from drug binding to material stability. But how do we quantify and understand these subtle yet powerful effects? This chapter dives into the local energy decomposition (LED) method, a state-of-the-art computational tool that breaks down complex interactions into chemically intuitive components – such as electrostatics, exchange, and London dispersion – at the local coupled cluster level of theory. LED reveals the role these forces play in asymmetric catalysis, protein-ligand binding, and even solid-state materials. We introduce the theory behind local coupled cluster computations and the framework of LED and its recent extensions and discuss several illustrative case studies.