We are increasingly giving away personal information on sites such as Facebook
As part of a major series on the BBC about the impact of the web, producer Jo Wade has been looking at the price we pay for free information.
'Numb Fingers.' 'Wind Beneath My Wings.' '60 Single Men.' 'Ceramic Ashtrays.' 'Depression and Medical Leave.' 'Dog that urinates on everything.' 'Foods to avoid when breast feeding.' 'Fear that spouse contemplating cheating.' 'How to kill oneself by natural gas.'
These are a few of the eclectic and sometimes disturbing internet searches made by the users of AOL, who believed they were using their computers in private.
The relationship with what we think is a free and largely private web; how we unreservedly put our innermost thoughts and queries into what feels like a very private space - sometimes thoughts we wouldn't dare share with anyone or even put down in a diary, comes at a price.
In May 2006, AOL released a file containing every search made by 658,000 of their users over the previous three months. It was part of a research project and each user was identified only by a numerical code to protect their identity.
But one reporter at the New York Times was intrigued by the potential value of data like this to governments or corporations.
Were these outwardly anonymous searches in fact so personal that they would reveal the identity of the searcher? David Gallagher turned detective to try and prove it.
After a few hours' work and using nothing other than these search terms and the telephone directory, he had correctly managed to identify his target.
It was a 62-year-old woman called Thelma Arnold from Atlanta, Georgia, who was understandably rather shocked and angry.
This story illustrates how we have become unwittingly complicit in a deal that is reshaping our world. Twenty years after its creation, the web appears to offer us unprecedented free access to knowledge and entertainment.
However this gift comes at a price and in the end someone has to pay.
Think back to the search terms you've put into a search engine in the last week. It's likely you can't remember most of them.
But as the AOL story shows us, it's these incidentals that, when pieced together, can give a surprisingly revealing picture of who we are.
If that information goes public - whether through accident or ill intent - we suddenly feel very exposed and very vulnerable.
How much would someone have to pay before you would let them read your diaries, find out what your religious beliefs, political leanings or sexual preferences were, or where your children go to school?
What many of us are not aware of is that we are freely giving away exactly this kind of information to websites that we use every day. More importantly, we are doing this on a massive scale.
In this digital era, where we spend an estimated £50bn a year (source: IMRG 2009) on online goods and services, we worry about data theft and online security.
But there's an even bigger, more important issue and that's how we give away information about ourselves every time we log on and how it is being used by powerful companies now shaping the web.
We need to ask ourselves whether we need to be concerned.
Every day in Britain millions of searches are carried out on Google for free. Every month we spend millions of hours on Facebook for free and read millions of articles from free newspapers.
But now look at it the other way round.
Millions of searches are carried out on sites like Google
Every day Google gathers millions of search terms that help them refine their search system and give them a direct marketing bonanza that they keep for months.
Every week Facebook receives millions of highly personal status updates that are kept forever and are forming the basis of direct advertising revenue.
Every month free newspapers plant and track a cookie tracking device on your computer that tells them what your range of interests are and allows them to shape their adverts and in the future, even content around you.
So you're not just being watched, you're being traded. The currency has changed.
The currency is now information - your information. Businesses can use that information to make big money.
Daily we hand over the minutiae of our lives in return for a convenient and free web.
It's been a slow, almost imperceptible shift in culture and in how we value privacy.
Few of us are really aware of the implications of these changes and this programme explores whether it is a trade worth making.
The third episode of the Virtual Revolution will be broadcast on 13 February at 2015 on BBC2