Fuel injection is a system used in internal combustion engines to deliver fuel directly into the combustion chamber or intake manifold. This process replaces older carburetor systems, providing more precise control over the fuel-air mixture, which improves efficiency and performance. In a fuel injection system, sensors monitor various engine parameters, such as temperature and air pressure, to determine the optimal amount of fuel needed. This allows for better fuel economy and reduced emissions, making it a key technology in modern vehicles, including those powered by gasoline and diesel.