"A few years ago, I was surprised to find out that my friend Peter Eckersley - a very privacy conscious person who is Technology Projects Director at the EFF - used Gmail. I asked him why he would willingly give Google copies of all his email. Peter pointed out that if all of your friends use Gmail, Google has your email anyway. Any time I email somebody who uses Gmail - and anytime they email me - Google has that email."
"LIKE it or not, your relationship with Google is becoming a lot more intimate. The company recently expanded its ability to combine data from its various services to create a highly detailed profile on you. Google says it's doing that to simplify its privacy policy and improve your experience on sites such as Gmail, Picasa, Google Plus and YouTube. But there's a business reason, too. Google gets a chance to use the data it collects to tailor ads that align more precisely with your interests, and those personalised ads are among the most lucrative for the company.
Before getting too worked up, it's important to understand what's happening.
"Google is a technology giant that provides a huge variety of services, many of which are free. Gmail, Google Drive and Google Hangouts can be used without paying a dime. Instead, pay by providing information about yourself, which Google can use for advertising. Though it started in search, the lion's share of the company's profits come from ads."