A radiator is a device used for heating the air inside your house. There are different kinds of home radiators - steam radiators, baseboard radiators and hot water radiators.
In a steam radiator, a boiler is used to heat water until steam is produced. Since producing steam by letting the water boil, takes time, one cannot expect consistent heating. This system can only produce intermittent heating and cooling for your rooms.
Vented baseboards are used for installing baseboard radiators. The metal fins at the vent openings expand the surface area. Heat is absorbed and radiated from hot water-filled pipes. Accumulation of dust on the metal fins produces an insulating effect. Now, for the air to circulate freely, you should maintain cleanliness.