The death of Charlotte Dawson and the possible role that online abuse played in her struggles with depression shows how damaging this behaviour can be.
The former model had told of her battles with depression and the abuse and harassment she suffered from users of social media website Twitter.
Since Ms Dawson's death, experts have pointed out that existing stalking laws could be used to respond to those who abuse people online.
Despite legal similarities, research is showing personality differences between online "trolls" and stalkers.
It seems like online abuse is now so common that any offensive or potentially harmful comment posted on social media is called "trolling".
The problem is, online abuse can range from one-off racist, sexist or otherwise distasteful comments to threats of rape and violence and sustained campaigns of harassment that cause significant psychological harm.
Lumping trolling in with cyberstalking obscures the different reasons that people have for behaving badly online and the different responses that might be needed.
How to best respond to a hateful or threatening comment probably depends on who is sending it to you and what they are trying to get out of it.
The terms trolling and cyberstalking do overlap as both involve repeated, online and harmful actions.
In academic literature, trolling is acting in deceptive, disruptive and destructive ways in internet social settings with no apparent purpose. Cyberstalking is using the internet to repeatedly target a specific person in a way that causes them distress or fear (reflecting descriptions of offline stalking).
Using these definitions, some trolls could be considered cyberstalkers, and vice versa. But evidence on trolling suggests the actions of a troll might meet different psychological needs to those of a cyberstalker.
Researchers from Winnipeg conducted a study earlier this month on the personality characteristics of internet trolls. In particular, they explored whether trolls reported the personality traits of:
•Machiavellianism - willingness to manipulate and deceive others.
•Narcissism - grandiosity and entitlement.
•Psychopathy - lacking remorse and empathy.
•Sadism - taking pleasure in the suffering of others.
They found clear evidence that trolling is associated specifically with self-acknowledged sadism, and to a lesser degree with Machiavellianism.
What's more, people who reported sadism tended to troll because they found it to be pleasurable. As the researchers concluded: "Sadists just want to have fun" and the internet is their playground.
The results of this study are remarkably different to what we know about cyberstalkers (and stalkers generally):
•Unlike trolling, there is a high degree of overlap between online and offline stalking, with 70 per cent to 80 per cent of cyberstalkers using both behaviours.
•There is no evidence to suggest cyberstalkers are motivated by sadism, though personality disorders involving poor emotional control and antisocial attitudes are reasonably common.
Research suggests that, rather than primarily taking pleasure in their behaviour, stalkers are more likely to be highly distressed and angry with the victim.
Although they may get secondary pleasure from it, stalkers who intimidate or threaten usually have the specific purpose of expressing their negative feelings and making the victim feel as bad as they do.
So if trolling and cyberstalking occur for different psychological reasons, does that mean that different responses are required? From the research to date, the answer is yes.
It seems trolls are in it for the "fun" of provoking a response, whereas cyberstalkers are more emotionally invested in pursuing the victim. This raises the possibility that the advice "do not feed the trolls" may have genuine support.
When the troll fails to provoke a response, he or she may look elsewhere.
However, ignoring the cyberstalker may have the opposite effect. Unlike the troll, they need a response from this victim. They can't just move on to another person because the issue that led to the stalking is victim-specific. Totally ignoring cyberstalking may not only inflame the stalker's emotions, but lead to an escalation in behaviour.
An immediate online response isn't advisable (it can be equally enraging for a stalker), but a cyberstalker will likely require some sort of response to stop the harassment.
Before a target chooses a response, they should think about who is harassing them and why they might be doing it.
If they think they have a prior relationship with them, if they are using multiple different methods to harass the person, or if it has gone on for more than a week, they may be dealing with a cyberstalker. If so, they may need to start recording evidence and consider whether or not to involve the police.
If this is a one-off, provocative contact from an unknown person, it may be a troll looking to provoke and the best thing to do is ignore it.
Trolls should be reported to the website host and where there is an explicit threat or where a person feels scared by the behaviour, save the evidence (take a screenshot and print it) and take it to the police.
Troy McEwan is a lecturer in clinical and forensic psychology at Swinburne University of Technology, Melbourne.