Fought back: Brisbane gaming journalist Alanah Pearce got her own back on the bullies by forwarding their rape threats to their mothers. Credit:YouTube So I'm surprised to be greeted by a 48-year-old woman with blow-dried blonde hair, a fitted blue dress and pearl earrings. She sits opposite me and orders a large skinny latte, midway through her morning commute to a marketing job at a multinational company. You don't look like an online troll, I say. "I think there's a troll living in all of us," she says. Online trolls are agents of chaos, gleefully upsetting people on social media sites, blogs and forums. The Equaliser, who asks not to be named, says she spends several hours some days raising hell online. Her husband reckons Twitter is ruining their marriage. She compares her behaviour to that of a drug addict: "They know it's crazy but they continue to do it." She smiles and says she tweets abuse because "it's a sport, it's an adrenaline rush". "I don't go out of my way to intentionally hurt people but if they are in the public arena I look at that as a license to kill," she says. "Twitter is a nasty, nasty place – don't get on there unless you're tough."

Besieged with abuse: Kim Walsh was ridiculed on Facebook when she gave birth to a baby a few hours after finding out she was pregnant. Credit:Louise Kennerley It is nasty out there: a survey released in October, by the United States-based Pew Research Center, found 40 per cent of internet users had been harassed online – from name calling through to physical or sexual threats and stalking. Kim Walsh, of Fairfield, was abused on Facebook in October, after The Sun Herald revealed she didn't know she was pregnant until a few hours before giving birth to daughter Shelby. Walsh had thought herself infertile due to polycystic ovary syndrome, which can cause irregular periods and obesity. Illustration: David Rowe Lurking among the many congratulatory messages on Facebook were users who called her "f***ing fat" and a "moron". "I would be lying to say it doesn't hurt a bit," Walsh says. "My husband calls them 'keyboard warriors' – all big and tough on the computer but if you see them face-to-face they don't say a word."

She struggles to understand why some people are so mean. "The only thing I think is that they are bored and want to feel better about themselves, by putting other people down." Inspired online petition: Charlotte Dawson committed suicide after being bullied online for years. Credit:Lee Besford Relatively little is known about the type of people who troll. A study published in September, by the University of Manitoba, in Canada, found trolls exhibit the personality traits of narcissists, psychopaths and sadists – taking pleasure in the suffering of others and lacking remorse or empathy for their victims. Trolls are like the Joker villain, operating as "agents of chaos on the internet", the study said. One of the authors described trolls as "everyday sadists" in an interview: "They are insatiably nasty. There is no reasoning with them. The more havoc they sow, getting more people to argue with them, the happier they are." Their chaotic behaviour can have dire consequences. Celebrity Charlotte Dawson, who committed suicide in Sydney in February, had long been attacked by trolls saying she should kill herself or self-harm. Some victims are targeted with rape and death threats. The abuse might spill offline – with victims receiving threatening phone calls or having their home address posted online.

The Equaliser says she "feels sorry for the Charlotte Dawsons of the world". She tells me that she, too, has been the victim of online trolls. Still, she delights in shocking and upsetting others. She seems incapable of empathising with the victims of abuse. "If the things people are saying about you on Twitter are making you sick, get the f**k off it," she says. She tells me she grew up in far north NSW, where it was "quite normal" to be called a "c**t" in the playground. Her Twitter account is "very tongue-in-cheek" and meant to be humorous, she says. "Having an opinion doesn't make me unlovable or a bad person." She likens herself to a "shock jock", who is deliberately provocative to bring attention to their chosen cause. Her favourite targets are Islam – she says her son served in the Australian Defence Force in Afghanistan – and Halal certification, which she claims is used to fund terrorism. "To a lot of people on there I am the voice of reason," she says, with no hint of irony. I talk to a handful of trolls for this article and find them to be perfectly pleasant and persistent, and in deep denial about their behaviour. They're the rabid underdogs, tearing at the heels of politicians and public figures. The world through the eyes of a troll looks unjust and cruel. Deep down, they fear no one is listening. When challenged, they play down their rants as colourful banter.

"Fundamentally, it is enjoyable for them," says clinical psychologist Troy McEwan. "In much the same way as graffiting something or setting small fires is probably enjoyable to some people. I think they don't genuinely believe it has an impact." Dr McEwan, from the Centre for Forensic Behavioural Science, at Swinburne University of Technology, suggests such behaviour is learned at an early age from peers and parents. "If people in your social circle think that being nasty is awesome and hilarious, that's teaching you something," she says. Women, in particular, bear the brunt of online abuse. "There are probably men who are getting abused or harassed or trolled online but it doesn't carry the same level of sexist or overt gender aggression," she says. Left-wing columnist on The Guardian Van Badham says she is harassed every day, online and offline – from sexualised and abusive tweets to phone calls and physical threats. She says she has built up a "demographic understanding" of her trolls, based on their tweets and other available online data. They're typically white men in their mid-50s, she says, of lower middle-class and "angry and frightened" about "the rise of female and feminist commentators". I message a man whom Badham nominates as a troll on Twitter and he calls me for a chat. Writing under the pseudonym "The Angry Socialist", he twice tweeted that he would like to see someone shoot her with a gun – most recently at the G20 meeting in Brisbane: "I'd love to see a police sniper take her out....I'd pay to see that!"

He tells me he is "about 65" and a former magazine editor, who has retired to the Gold Coast. He denies being a troll - it's Badham and her peers who are the trolls, he reckons. "All those woman all hate conservatives...Anyone who disagrees with Van is immediately labelled a troll or racist or bigoted, then blocked." Soon, I am bombarded with tweets and emails from several men who claim to have been verbally abused by Badham. They send me a small selection of her 103,000 tweets, in which she is quick to slam someone with a contrary opinion as sexist or racist or a c**t. She calls Prime Minister Tony Abbott a "lying, sexist c**t". Some of her tweets are abusive and unprovoked, and her language extreme. "I am not a troll - I'm a vicious c**t," she writes online. Badham tells me that the meaning of trolling has evolved, from someone "saying the most offensive thing possible", to "anonymous abusers" seeking to humiliate and harass a specific target. "Those are tweets I sent amid thousands of insults and harassment and stalking levelled at me," she says. "These guys stalk me and harass me and intimidate me, and I am the bad person now?" None of it seems decent to me. But there are tiers of trolling. There's the foul language used by Badham or, indeed, The Equaliser. Then there's a tweet saying you would happily see someone shot dead.

The Angry Socialist insists he meant no harm by his sniper comment. He tells me it "got a lot of retweets", as if that is validation enough. "Some thought it was hilarious," he says. He tosses out the line that Australia is a free country. "We are allowed to say these things in Australia," he says. Over our 47-minute conversation, he rails against feminist "fright bats" and the "great hoax" of global warming. He likes that people are listening to him. But soon after we speak, he deactivates his Twitter account. "I don't need all this drama in my life," he tells me later. He suggests he will be back on social media soon, in another anonymous guise. That's the thing about trolls - there's no shortage of shadowy places online for them to fester. "I'm very angry, so what [else] does an angry person do," he says. "We're all play acting in life, aren't we. I'm pulling the angry face...It's like I am messing with their minds." - TV personality Charlotte Dawson committed suicide in February, aged 47. She was the target of cyberbullying for years, saying it left her feeling helpless and depressed. She tried to kill herself in 2012 after receiving a barrage of online abusive messages and death threats. She continued to fight depression but was found dead in her Woolloomooloo apartment. Her death prompted thousands of victims of cyberbullying to come forward and share their ordeals. An online petition entitled Charlotte's Law attracted more than 174,000 supporters calling for tougher laws on cyberbullying.

- Rugby league star Robbie Farah was abused by a Twitter troll in September 2012. The anonymous Twitter user sent him "vile" comments about his late mother. Farah reported the abuse to police and the account was shut down by twitter. He called for stricter laws around social media to make people accountable for their comments. - Brisbane gaming journalist Alanah Pearce received threats of violence and sexual assault on Facebook in November, mostly from young boys using their personal Facebook accounts. The 21-year-old communications student forwarded the messages to the boys' mothers on Facebook, one of whom apologised for her son's behaviour. - Sydney florist Fiona Stewart Brown was convicted in October 2014 after making "obscene", "vindictive" and "malicious" comments in online blogs. A magistrate found her guilty of "using a carriage service to menace, harass or offend" after she tried to destroy the reputations of staff at the former Insolvency & Trustee Service Australia, who were handling a case in which she was a creditor. She has appealed against the verdict. - British woman Brenda Leyland was found dead in a hotel in October 2014, soon after being revealed as a remorseless online abuser of Kate and Gerry McCann, whose daughter Madeleine went missing in Spain in 2007. Ms Leyland, 63, sometimes posted more than abusive 50 tweets a day, insinuating that the McCann's were implicated in the three-year-old's disappearance. Ms Leyland was described as a likeable, church-going woman, who developed an obsession with the case.

- Isabella Sorley, 23, and John Nimmo, 25, were jailed in England in January 2014 for abusing feminist activist Caroline Criado-Perez on Twitter. Among Sorley's tweets to Criado-Perez were "die you worthless piece of crap" and "go kill yourself". Nimmo made references to rape and wrote "I will find you :)". Sorley's lawyer said she was a "victim" of new technology and did not understand the impact of her actions. Nimmo's lawyer described him as a "somewhat sad individual" and social recluse, with "some level of learning difficulties", who had been bullied at school.