From Wikipedia: In Internet slang, a troll is a person who sows discord on the Internet by starting arguments or upsetting people, by posting inflammatory, extraneous, or off-topic messages in an online community (such as a forum, chat room, or blog) with the deliberate intent of provoking readers into an emotional response or of otherwise disrupting normal on-topic discussion.
This sense of the word troll and its associated verb trolling are associated with Internet discourse, but have been used more widely. Media attention in recent years has equated trolling with online harassment. For example, mass media has used troll to describe "a person who defaces Internet tribute sites with the aim of causing grief to families."
Well done I was going to add to that about the media perception of what trolling is but you beat me to it, yes, online harassment isn't trolling, many news journalists know nothing about the internet so they don't know the different, plus they're morons so that doesn't help things much.