The arrangement of molecules in a magnet makes itself a magnet.if u want to know further,try searching "Ewing's molecular theory of magnetism".

all the molecules of a magnetic substance is an independent magnet. in an unmagnetized magnetic substance, the molecular magnets are randomly oriented. they form dosed chains so they neutralize the effect of each other. these chains are called domains and each molecular magnet is called dipole.

when a substance is magnetized, the molecular magnets are arranged in one direction by breaking the domains. the end where all the north poles of the dipoles are present becomes the north pole of the magnet. the other end where south pole of the dipoles are present becomes the south pole of the magnet.

when the magnet is strongly heated or hammered the kinetic energy of the molecules increases and therefore the molecules alignment gets disrupted and the molecules go back to the closed chain arrangement to form domains and thus the magnet gets demagnetized :) thank you.

A superconductor.

Aluminium is not attracted by a magnet, due to the molecular structures that it forms. Metals which can be readily attracted include iron, cobalt, and nickel, although compounds of these will demonstrate significant differences in magnetism.

As we know every particle is made up of tiny particles called atoms,each magnet is made up of tiny particles called Molecular magnets.Each of them acts as a individual magnet with North and South poles.There arrangement decides the polarity of the magnets