The document summarizes the key components of an internal combustion engine exhaust system. It discusses how exhaust gas is emitted from fuel combustion and transported from the engine through the exhaust manifold. It then describes the three main functions of the exhaust system: to channel waste gases out of the engine; reduce engine noise; and clean emissions. It lists the main pollutants from exhaust and the key components of an exhaust system, which include the exhaust manifold, catalytic converter, muffler, and tail pipe. The exhaust manifold collects hot exhaust gases from the engine and burns any remaining fuel. The catalytic converter uses a catalyst to convert harmful compounds into harmless ones. The muffler then cancels engine noise before the exhaust is expelled through the tail pipe.