From The New York Times article:

Trolling can refer to a range of online troublemaking, including posting provocative comments and purposely marring others’ online experience, and it can include attacks on people as much as on software. The practice of ruining things for others, originally known as griefing in the online gaming world, has become a sadly abundant element of internet life.

“Folks who are griefing or trolling feel like they are in a secondary universe that isn’t the same as the real world,” [Bogost] said. “It was a ‘safe space’ for them, in which they did horrible things.”

Read the full article at The New York Times here.