Trolls are people who try to deliberately provoke others, usually by posting abusive, annoying or otherwise inflammatory stuff to try to provoke other users, but in most cases are doing it purely to provoke rather than actually believing what they're posting (as opposed to misogynists, rape deniers, xenophobes, racists etc. who are just assholes), which is why they often shut up and go away if you ignore them. It's experienced by men and women, but I do think women are targeted more often - some men, unfortunately, do seem to get a kick out of trying to offend or upset women.