In the modern day, this term is widely used across the Interwebs to describe a user or member who purposefully enrages you or others for fun. (2)
A term used on the Popular channel =3 Vlog on YouTube, where the troll is a common other voice usually saying how things are "fake and gay". (No Example)
Bi: I'm Trolling.
(2) Troll: You're Gay!
User: Fuck off!
User: FUCK OFF TROLL!
MAN B:No, decided to take a poop instead.
Trollin' can be done anywhere, though it's mostly done online. And is the simple yet effective task of annoying the fuck out of someone, untill they give up or get mad. Usually resulting in the person leaving the forum/chat room.
It is often speculated as to what Trolls get out of Trollin'. Though most Trolls will tell you that it brings then gleeful joy to successfully Troll a stoopid.
To avoid being Troll'd, simply do not feed the Troll.