I use Googlemail for my e-mail. As is the case for millions of others, it is the hub of my online existence.

I have just sent myself an e-mail saying that I wanted to buy a new bed. Within four minutes this link appeared in the small ad box at the top of my inbox: Temperature-pedic 70% off www.eBed.com/Tempur-Pedic - Mattress Sale: Get Free Delivery, Free Pillows, No Tax & Much More.

What has happened is that Google has digitally "crawled" my inbox, noted that I was writing about beds, and sent me a targeted advert. To some this is very scary. Google knows what I am writing about all the time. In theory, it knows that I have just been to the doctor for a check-up.

So why do I use Gmail? Because, for me, it is the best e-mail service around. It delivers great features and is improving all the time. Just this week it launched a service where you can use your e-mail offline, so when the connection is down, you can still get lots of work done.

I have made peace with myself over Google's "invasion of my privacy" because of the service it provides. This deal, or "value exchange", is at the heart of Google's success. They have a near monopoly in search because most people have done this deal. Billions of times a day, people entrust Google with the details of their lives. Every time you enter "acne", "coffin" or "new car" into the Google search bar, you are telling the Googlebots a tiny part of what you are up to.

Many people, I suspect, don't think about this and when they do, they don't care enough to change to a different search engine.

The reason is because, by and large, people trust Google not to do anything evil with their anonymised personal information. So far, Google has earned that trust. It sets out clear policies for how much information is retained and for how long. It has videos that explain such things, if you care to view them. Its track record in not leaking data is better than most companies and certainly better than the Government. It has used this trust to sell ads and create a whole host of ways of putting the world's information in the hands of users: the best example of this is Google Earth. By disseminating knowledge, the company's founders believe they can help humanity. While some may laugh at this lofty ambition, they are serious. Eric Schmidt, Google's CEO, said in an interview last year: "The goal of the company is to change the world."

But what worries people is that we have to take it on trust that Google will not use all that personal information in a way we object to in the future. Google's moral stance is that openness is good, secrecy is bad. But in 2006 it launched a censored search engine in China that did not throw up any results about Tiananmen Square or Falun Gong. It compromised.

Many arguments ensued about whether this was a good or a bad thing. The point is that, as Google grows in influence through its products, as its profits and innovation drive it deeper into the fabric of how we live our lives on the internet, the company will have to make more moral compromises, because human interaction is not as black and white as the company's mantra of "Don't be evil".

I just have to take it on trust that their definition of evil will remain the same as mine.

Explore Tech & Web

• Personal Tech

• The Web

• Gadgets & Gaming