Account 'takeover' is the most common sort of identity theft, The Financial Times reports, quoting findings from Experian. 'Takeover' means that a fraudster just starts using someone else's email account or bank account.
They can also go on to set up other accounts in that person's name, so they can run up big bills - which 'can take a long time to sort out with creditors'.
The illegal trade in personal information is a big worry these days. It seems almost 20 million bits of personal data were illegally traded online in the first six months of 2012 alone.
The opportunities for fraudsters are largely due to the sheer number of online accounts that people have these days. On average, UK residents will have around 26 accounts, while 25-34-year-olds are more likely to have 40.
There's also the issue of behaviour: when people don't take the right steps to protect themselves and their accounts, they can make things much easier for the criminals.
Around 60% of internet users, apparently, don't log out of websites when they're finished, while around 25% never check whether a website's secure (as shown by the 'padlock' image).
And around 25% just use the same password for most of their accounts, rather than coming up with a unique password per site.
So, apart from logging out, looking out for the padlock and using separate passwords, what can you do to foil the fraudsters? For tips on protecting yourself online, check out some of the guides we have written: