Ferromagnetic Materials

In investigation 4, i worked with iron fillings. I magnetised and demagnetised iron fillings inside of a straw. While the straw was magnetised, we put it next to some more iron fillings. We saw that when the iron fillings lined up in one direction, it meant that the straw was magnetic. However, When they were scrambled, it wasn't magnetic. In addition, we saw that when something is magnetised and you place a compass near it, then the needle of the compass will always point to the magnetic object. However, I'm still a little confused as to how magnetising and demagnetising occur. So, I will try to get the answer to that question.