what are trolls on the internet?

[Amy]

Like,on some questions i answer other people have put 'Troll!' or 'Trololololol'..
and in newspapers sometimes it says things like 'A troll put 'Stupid woman' on her twitter page'. What does 'an internet troll' actually mean!?

[jane smith]

a troll is someone who posts inflammatory,[2] extraneous, or off-topic messages in an online community, such as an online discussion forum, chat room, or blog, with the primary intent of provoking readers into an emotional response[3] or of otherwise disrupting normal on-topic discussion