Click reporter David Reid asks why search engines are so keen to keep hold of our personal data.
Search engines have given many people a very good way to satisfy their curiosity about any and every subject. But, as many people are realising while they discover the world, search engines are finding out all about them.
This was vividly illustrated in August 2006 when AOL accidentally published the details of millions of keyword searches that 650,000 of its subscribers had carried out over a three month period.
The data leak revealed many people's online lives in remarkable detail. One man's life became an open book revealing the sad plot of his failed marriage, desire for revenge, and obsessive jealousy.
Search engines are taking on the role of confessor and counsellor albeit one that shares information people would prefer remained private.
"I am not sure people know that such operations are taking place," said Meryem Marzouki who studies the relationship between people and technology at France's Universite Pierre et Marie Curie.
"This is a general problem with free services," she added. "You have the impression that you don't pay for this, you don't pay. In fact, you pay a very high price, because you pay with your own privacy, your own intimacy. You pay with yourself."
Search engines have a good reason for gathering data about what people look for. Most make they money via advertising and use the data they gather to ensure you see adverts related to those searches.
But for many it is unclear why search engines need to record and store the search terms people use or to link it to the IP address of a computer, and therefore to us.
The amount of personal data being collected is beginning to alarm European data protection bodies, made up of national watch-dogs, including France's CNIL.
"Normally, they will only use this information to send you personalised information or personalised advertisements. This is how they are efficient and this is how they make money, which is fine," says Gwendal LeGrand, an advisor at CNIL - the French national data protection organisation.
However, he said, there was a risk if the reason for collecting the data changed.
Potentially, they have the means to use this information in a way that will learn a lot about the habits of the users," said Mr LeGrand. "This can potentially be dangerous."
As the dominant search engine, Google has come in for most criticism about the data it holds and what it does with it.
Some go as far as to claim that all Google is interested in is gathering personal data.
Google denies this and in mid-June announced it would only be retain search data for a maximum of 18 months.
Google defends its need to gather data by saying that it is a defence against some types of fraud.
Peter Fleischer, Google's global privacy counsel, said privacy would be served if it gathered no data about searchers and searches but that would mean a jump in the amount of fraud perpetrated online.
"The net is like the real world, there are bad people and good people out there and we have to be prepared for dealing with both," said Mr Fleischer.
For some the amount of data being gathered by Google is getting too much. Alongside its retention of data about searches and searchers goes information about the text of e-mail messages sent to and from GMail.
Said Mr Fleischer: "We are committed to being transparent with our users. We are trying to be transparent about our privacy practices.
"We try to communicate with our users in the clearest and simplest language. I think those are principles we need to adhere to," he said.
It is easy to forget the advantages of data retention. Google has launched a web history services that lets people browse and edit the list of sites they have visited in the past.
Google users can opt in for this service but opting out of others can be tricky.
It is possible to remove the cookies, small text files, on a computer that sites use to remember return visitors but not everyone knows about them or has the courage to mess around with their computers in this way.
With Web 2.0 now moving so many of our desktop applications, and therefore data, online, campaigners feel we would do well to get these privacy issues sorted out sooner rather than later.