Magnetization and Demagnetization - different ways

In the following paragraphs, different ways of Magnetization and Demagnetization are listed.

Different Ways of Magnetization

A ferromagnetic material can be magnetized by placing it inside a solenoid and gradually increasing the direct current (d.c.).
This increases the magnetic field strength in the solenoid (the density of the field lines increases), and the material becomes magnetized.
Reversing the direction of current flow reverses the direction of the magnetic field and reverses the polarity of the magnetization.
Hammering a magnetic material in a magnetic field causes magnetization
‘Stroking’ a magnetic material several times in the same direction with one pole of a magnet will also cause it to become magnetized.

A magnet can be demagnetized by placing it inside a solenoid through which an alternating current (a.c.) is passed and gradually reduced.
Dropping or heating a magnet also causes demagnetization.
In the absence of a magnetic field, Hammering a magnetic material causes demagnetization.