Cyberclinic: Why do spelling errors take you to dodgy sites?

In a perfect world, we would mistype a site address and immediately be notified of our careless error – but the internet doesn't work like that. There's nothing to stop people registering whatever domain name they want, and when thousands of people every day are accidentally ending up at www.mysoace.com, instead of www.myspace.com, it's no surprise that some enterprising souls have snapped up the site in question and started to make money out of our carelessness.

Of course, these sites are only hit by people either guessing at an address, or putting .com instead of .net or .org, or misspelling, or hitting two keys at once. While some companies are wise to this (www.yahooo.com redirects to www.yahoo.com, and www.gooogle.com redirects to www.google.com) it would be laborious, expensive and futile for anyone to try to register all conceivable misspelt versions of their address.

Normally, this isn't much of a problem. Most people quickly notice their mistake, type in the right address and proceed. And, as "Lob" points out on the Cyberclinic blog this week, typing out URLs is becoming old hat: "Most sites I visit are on an RSS feed. I explore other links via these – I hardly ever do it longhand."

But as kids are (perhaps) more likely to misspell than adults, it's a worry that some sites throw up off-colour links. A misspelling of www.hotmail.com may reveal the kind of lurid pornographic content that would upset children – and their parents. Spam, viruses and adware are also common, as "Ant" writes in our blog: "Geeks like myself are wise to them, but the same probably can't be said for people who are significantly younger, older or just more naive."

Policing "typosquatting", as it's known, is virtually impossible. But McAfee's Site Advisor (free download at www.mcafee.com) claims to be fighting the menace by yellow- or red-flagging any site triggering its typosquatting criteria. This will, presumably, be a blow to the person now making money out of www.macafeee.com.

What are the best free alternatives to Microsoft Office? And could your website cope if it suddenly became incredibly popular? Email me at cyberclinic@independent.co.uk or join the discussions on the daily technology blog, independent.co.uk/cyberclinic