However unwittingly, you share personal information with complete strangers every single day - via the internet.
The issue of internet privacy has been in the news because Google has changed its rules to allow information to be shared across all its services.
Peter Barron at Google emphasises that all personal information is stored safely and, if you do not want to store data, you do not need a Google account to use its search engine.
But Google is not the only internet service busy farming out data and this raises the question of the invasion of people's rights.
"Companies like Google, Facebook, Yahoo and Microsoft are expanding their data collection techniques and they are not telling consumers and citizens why," says Jeff Chester, of the Centre for Digital Democracy.
"Increasingly a system has been created that tracks us wherever we go, whatever we do, and sells us to the highest bidder."
Simon McDougall, of the financial service consultants Promontory, thinks it is right that people should be concerned, although switching from Google to another service provider would make little difference.
He points out that many people have used free services on the internet for a very long time and they have not really thought about how that service is being paid for.
"If you pay money for a product, you get a product. If you do not pay money for a product, you are the product," he says.
"More people are realising there is a pay-off and some people will be happy with that whilst some people won't be," he adds.
The issue is about how you pay for online services and whether you are happy to sacrifice privacy for getting a service for free.
Mr Chester maintains it is about the philosophy and ethics and the future of democracy.
"Our privacy as citizens and users throughout the world is threatened by this powerful pervasive commercial surveillance system that is being created without our awareness and without our consent and that has nothing really to do with paying for online services," he says.
One of the the key battles is between the European and American interpretations of privacy.
"In Europe, privacy is enshrined as a civil right, based on the experience that happened in Europe with Hitler and with communism, and you have embedded important civil safeguards around privacy that places the system in balance between the citizen and the corporate sphere and the government," explains Mr Chester.
"In the US, while privacy is a form of a right, it is in fact the free market which determines most of the policies when it comes to the internet."
He believes it is the Europeans who are driving the policy debate, while the US strategy is to lobby the Europeans to accept the idea that there can be self-regulation, to trust the Googles and Facebooks and let this market grow.
"I see a lot of these initiatives and lot of this data collection being driven by fairly straightforward commercial imperatives," he says.
He is resigned to the fact that the battle for greater privacy has been lost.
"We are already deeply embedded in the digital media systems operating all over the world," he says.
"The expansion of data collection throughout Europe and Asia Pacific in the last two years is stunning. All we can do now is come in after the fact and try to place a few safeguards so that our sensitive information is protected," he notes.
Mr McDougall is not so pessimistic.
"I do not see a lurking superstructure behind all of this," he says, "But I do see an awful lot of new data collection, new ways of using that data, and some of them are very concerning."
But should people really be concerned about releasing a bit of data onto the net?
"I think so, because we don't know where all our information is going to end up," says author Frank Ahern, who claims to be able to rub out, or at least disguise, unwanted online identities.
"The users themselves are problems as well," he says "Because they post, blog, tweet and do everything else also."
There was a time when people's lives were transient - they left no trace, but now we are all leaving traces constantly.
"The minute you wake up and turn on the light there is a trace - of electricity," he says.
"You log onto your computer, you walk out of your building, your building might have a camera; you walk down the street, there is a camera there; you walk into a store, there is a camera there," he says.
He mentions how he recently read a newspaper article about an app that was extracting photos from people's mobile phones and how those people had no clue about it.
"I think the biggest issue is that we as users just have to click 'Yes' and a lot of times most people click 'Yes' without reading what the privacy policies are," Mr Ahern says.
But there are now a lot of skeletons coming out of the cupboard.
Most newspapers in the world are posting every newspaper they have ever printed, so people are finding that things they did in the past are being made public.
He points out that one mistake in one blog, can be in three million blogs in nine million websites within hours.