Selective Catalytic Reduction (SCR) is a technology used to reduce harmful emissions from diesel engines. It works by injecting a solution of urea into the exhaust stream, which reacts with nitrogen oxides (NOx) in the presence of a catalyst. This process converts NOx into harmless nitrogen and water vapor, significantly lowering pollution levels. SCR systems are commonly found in vehicles and industrial applications to meet stringent environmental regulations. By improving air quality, SCR plays a crucial role in reducing the impact of diesel engines on the environment, making them more sustainable and compliant with emission standards.