I am assuming you do not mean the ugly fantasy creature, that can be found living under bridges, stalking billy goats?
A troll is supposed to be someone who will use offensive or inflammatory language with as sole purpose of getting other people worked up. Imagine someone posting “Hail Satan” in a Christian chat. Or, you know, this:
A true troll will say anything and everything if he knows it will get people angry. That’s why they say ‘don’t feed the troll’. If you ignore it, it will go away -in search of other, more excitable targets. True trolling is an art form. As you can see in the comic above, the point is to get a disproportionate reaction.
These days though, anyone getting into a heated debate is called a troll. They’re not. A troll won’t get into a heated debate, because they don’t troll from conviction, but for sport. These people writing long responses on stuff are writing from conviction. There’s a lot of names you can call them, I have a couple of names I am found of calling them, too, but they are not trolls.