Substances that are attracted strongly with magnetic field are called ferromagnetic substances, such as Cobalt, Nickel, Iron, gadolium, chromium oxide, etc. ferromagnetic substances are permanently magnetized. Metal ions of ferromagnetic substances are randomly oriented in normal condition and substances do not act as a magnet. But when metal ions are grouped together in small regions, called domains, each domain acts as a tiny magnet and produces strong magnetic field, in such condition ferromagnetic substances becomes a permanent magnet.