Expect trouble if you tweet

show any respect for it.

Demanding the right to exercise one’s freedom of speech on Twitter is like asserting the right to self-expression by strolling into a fundamentalist mosque in northwest Pakistan wearing a bikini.

The best you could hope for would be a fleeting moment of satisfaction, knowing you had struck a blow for individual rights, before you were decapitated.

EVEN more perplexing than feminists’ insistence on their right to attract rape threats, and infinitely more tragic, is the addiction of vulnerable teenagers to social media sites where they are taunted and humiliated, sometimes to the point of suicide.

The Latvian-based website ask.fm seems to be the principal offender. The deaths of four British teenagers have been linked to the site, which allows semiliterate trolls to place vicious messages such as ‘‘go die u pathetic emo’’ and ‘‘u ugly – go die evry1 wuld be happy’’.

The solution, for any teenager being victimised, seems blindingly obvious: just don’t go there.

But they seem incapable of tearing themselves away. Here is the bewildering thing. Affected teenagers seem gripped by an addictive malaise which, like self-mutilation and eating disorders, defies logical explanation – as does the unrelenting malice of the perpetrators.

This is the dark side of the digital revolution.

The internet may have empowered people by providing access to information on a scale never before imagined but it has also created unforeseen opportunities for those bent on doing harm.

IN THE course of deleting hundreds of spam emails from my computer recently, I noticed a peculiar thing.

A large proportion promised ways to shed weight, backed by the irreproachable authority of celebrities such as Britney Spears, Beyonce and Jennifer Aniston.

Paradoxically, others held out the prospect of miraculous weight gain – but only in a part of my anatomy that propriety precludes me from mentioning.

These things seem to go in cycles. For a long time, most of my spam emails purported to be from various banks and urged me, in comically bad English, to click on a link so that I could remedy a pressing problem with my account. Those have now abated, to be replaced by emails assuring me that with an enlarged mumblemumble, I will induce paroxysms of ecstasy in my sexual partners.

The really worrying thing is that, obviously, enough mugs respond to these emails to make the spammers’ efforts worthwhile.