The term "common rail" refers to a fuel injection system used in diesel engines. In this system, a single high-pressure rail supplies fuel to multiple injectors, allowing for precise control of fuel delivery. This enhances engine efficiency, reduces emissions, and improves performance. Common rail systems enable multiple injections per combustion cycle, which helps in better atomization of fuel. This results in smoother engine operation and lower noise levels. The technology is widely used in modern vehicles, contributing to the overall advancement of diesel engine design and performance.