The next click summons a Web page asking for address and phone number.

FORBES: E-Commerce Stinks

BT, Britain's telecoms incumbent, which in 2000 announced that it had a patent on hyperlinks, a technology that allows people to click on a web-page link to go to another web address.

ECONOMIST: The arms race

When a user clicks on an online ad, several pieces of data are transmitted, including the web address of the page where the user saw the ad.

WSJ: MySpace, Apps Leak User Data

Other times, though, people's names were simply included in the title or address of the Web page.

WSJ: They Know What You're Shopping For

Another Google-dodging feature in the new browser: Highlighting a street address on a Web page launches a map, with the default set to Microsoft's Live Maps (though you can change this default to Google Maps).

FORBES: Magazine Article

To join up data points into a context, common identities are required (for example, a web page view can be given a geographical location by joining up the IP address of the page request with that from the IP address in an IP intelligence database).

FORBES: Taking Stock of Data Markets: A Survey of Four Options

The apps were using a common Web standard, known as a "referer, " which passes on the address of the last page viewed when a user clicks on a link.

WSJ: Facebook in Online Privacy Breach; Applications Transmitting Identifying Information