Criminals need only three pieces of personal information to steal someone's digital identity to commit fraud, security services firm VeriSign has warned.
The UK Serious Organised Crime Agency (Soca) estimates online fraud is costing UK internet users around £3.5bn a year.
Some 11% of the UK's online community has been a victim of fraud in the past year, according to research by VeriSign.
Together, these statistics demonstrate the size of the fraud problem and how important it is to be vigilant, said Matthew Bruun, security expert VeriSign.
"Soca's research further highlights how criminals are continuing to widen the techniques they use to target their victims, with online fraud now a major industry," he said.
The trend for targeting dating sites, where users frequently input personal information, is especially worrying, said Bruun.
Anyone using these channels should take special care, both by reading a site's security policies and not passing on sensitive information, such as their date of birth or home address, to people they do not know, he said.
Checks for staying safe online
• Green address bar: this signifies that this site has undergone extensive identity authentication so that you can be confident it is the site it claims to be
• Trust marks: popular trust marks such as logos can indicate important things about an online business.
• Check the URL: look out for sites that do not contain a company's name immediately before the .com or relevant suffix.
• Does it look genuine? If a website seems poorly built or programmed and does not contain any verifiable security information, it may be a fake.
• Spell check: Be aware of sites with obvious and abundant typographical errors; many phishing and spoofing websites originate in foreign countries.