Google could be making as much as $500 million a year from users' dodgy spelling.
For years, 'typosquatters' have been registering misspelled versions of popular website names in the hope of attracting clumsy typists to their sites. If they get enough visitors, they can attract advertising via Google, with Google getting a cut.
And now two maths buffs at Harvard University have worked out just how much this advertising is worth to Google.
Tyler Moore and Benjamin Edelman looked at the 3,264 most popular .com sites, and then found 285,000 typosquats that were exploiting them.
They used software to crawl the sites and work out just how much they might be making, and what Google's share would be. On the assumption that the world's top 100,000 websites were suffering the same rate of typosquatting as the ones they studied, they worked out that Google was making $497 million per year.
Thee authors say that if they can identify these dodgy sites, then so can Google.
"The overwhelming majority of typos are easy to recognize, by hand or using straightforward automation. At the same time, with typo domains highly concentrated at a few large domainers and ad platforms, intermediaries could signiﬁcantly discourage the registration and use of typo domains if they were so inclined," they say.
"We ﬁnd that typosquatting is highly concentrated: Of typo domains showing Google ads, 63 percent use one of ﬁve advertising IDs, and some large name servers host typosquatting domains as much as four times as often as the web as a whole."
There's a paper on their findings, here.