More than half of Britons admit making their online passwords easily available on the internet and never change their details unless prompted to do so, research has shown.
Credit reference agency Experian warned millions of people were leaving themselves open to identity fraudsters by being too relaxed about the information they publish on online dating profiles and social networking sites.
Three of the most regularly used passwords - town of birth, date of birth and name of past schools - also feature in the top 10 personal details which people publish on their online profiles, the poll found.
The survey of more than 2,000 adults online found 18% would publish their town of birth on internet profiles, but only 3% would give this same information to a stranger over the phone.
Almost one in four people (24%) would publish the names of their past schools online, while just 1% of people would provide this information over the phone.
And 27% would publish their date of birth online, with 23% of those surveyed willing to tell it to someone over the phone.
More than half (51%) of those surveyed last month said they used the same password for some or most of their online accounts and 57% admitted using data easily available on social networking and dating sites as their password.
The poll also showed half of Britons (52%) never change their passwords unless they believe their account may have been compromised or have been prompted to do so.
Pete Turner, of Experian which runs ProtectMyID to help prevent identity fraud, said: "The message of ID fraud is still not being heard.
"The internet is accessible to almost everyone and as the number of users grow, so do those using it for criminal purposes. Users need to be aware of what information they are giving out online and who might be accessing it."