Raising further questions about privacy on the internet, researchers including those of Indian origin have found that a person's online behaviour can be identified by linking anonymous web browsing histories with your Facebook, Twitter and Instagram profiles.
"We show that browsing histories can be linked to social media profiles such as Twitter, Facebook or Reddit accounts," the researchers said.
"It is already known that some companies, such as Google and Facebook, track users online and know their identities," said Arvind Narayanan, an assistant professor at Princeton University in the US.
However, those companies, which consumers choose to create accounts with, disclose their tracking.
The research shows that anyone with access to browsing histories – a great number of companies and organisations – can identify many users by analysing public information from social media accounts, Narayanan said.
"Users may assume they are anonymous when they are browsing a news or a health website, but our work adds to the list of ways in which tracking companies may be able to learn their identities," said Narayanan.
Narayanan noted that the US Federal Communications Commission recently adopted privacy rules for internet service providers that allow them to store and use consumer information only when it is "not reasonably linkable" to individual users.
"Our results suggest that pseudonymous browsing histories fail this test," the researchers said.
They note that online advertising companies build browsing histories of users with tracking programmes embedded on webpages.
Some advertisers attach identities to these profiles, but most promise that the web browsing information is not linked to anyone's identity.
The researchers wanted to know if it were possible to de-anonymise web browsing and identify a user even if the web browsing history did not include identities.
They decided to limit themselves to publicly available information. Social media profiles, particularly those that include links to outside webpages, offered the strongest possibility.
The researchers created an algorithm to compare anonymous web browsing histories with links appearing in people's public social media accounts, called "feeds."
"Each person's browsing history is unique and contains tell-tale signs of their identity," said Sharad Goel, an assistant professor at Stanford University.
The programmes were able to find patterns among the different groups of data and use those patterns to identify users.
The researchers note that the method is not perfect, and it requires a social media feed that includes a number of links to outside sites.
However, they said that "given a history with 30 links originating from Twitter, we can deduce the corresponding Twitter profile more than 50 per cent of the time."