A troll in the old days is a word used by people who cannot handle any attack on their opinions.
So a "troll" was a person who enjoys to debate any topic with people on the internet. But as people can see account names, over time it becomes evident that one person basically argues with everyone opinions, seemingly always having the opposite view for the duration of the thread. This person is then just called a troll.
Which is sad, at school we had debates all the time when i was like 13-15 or so, the teacher told us a topic and who would argue for each side, this i think is one of the best things to do IMO, as it expanded my mind that their are always different points of view to every topic, to think critically and to always question why.
Over time i encountered many people with such strong views, at the same time i encountered people who have no idea how to do things i considered simple (lets say PC related stuff, and the simple kind)... When arguing or when trying to teach i learned the most important thing which ties in to my first point.
I do not know exactly what kind of physiological problem this is but there seems to be some sort of mental block in place which the majority of people have, that 1) prevents people from learning anything, and 2) prevents any attempts to influence opinions. The latter i could see all the time, when i argue i am not really of any strong opinion one way or the other, i just try to find the best approach, it is a game, and i love to win games. I notice people become defensive quickly and cannot use proper reason or logic.
For number 1, i notice all the time what i suspect to be exactly the same problem, when i tried to teach people the most simple stuff they have something which makes them feel uncomfortable and they basically cannot remember the simplest of things because they are actively fighting it.
So when someone insults or argues with your opinions or beliefs, just call them a troll and be confident in yourself.