What is ferromagnetic substance?

The substances, that contain a large number of unpaired electrons are attracted strongly by the magnetic field due to which they can be magnetized permanently. Such substances are known as ferromagnetic substances.

For example- Iron, cobalt, nickel, and some alloys or compounds containing one or more of these elements. 

These materials are used in a wide variety of devices essential to everyday life, for example, electric motors and generators, transformers, telephones, and loudspeakers.