A radiator is actually a type of heat exchanger, which is used to transfer the heat from the hot coolant flowing through it to the air blown by the fan. A radiator is generally consists of the core, pressure cap, outlet and inlet tanks as well as the transmission cooler.
Today, most cars use aluminum radiators, which are made of flat aluminum tubes with brazed thin aluminum fins. The coolant flows from the inlet to the outlet through a number of parallel tubes. The heat sink conducts the heat in the tube to the air flowing through the radiator.
Then why is the radiator important? A radiator is important as it is playing the part of the major way to dissipate the heat during engine operation. Radiator failure can cause serious engine damage and overheating. It is worth mentioning that most cars billowing smoke on the roadside are actually caused by radiator trouble.