"Lawmakers and the Federal Trade Commission are being lobbied to intervene to help settle differences between some advertising industry representatives and privacy advocates over how to implement a “do-not-track” option giving consumers the choice of whether they want to be tracked online.
Many companies now track consumers by placing text files called "cookies" on their computers when they visit certain websites in order to tailor ads to them based on their preferences. In response to the growing use of online tracking for advertising and market research, many privacy advocates have called for giving consumers a do-not-track option. The idea gained momentum after the FTC first endorsed the idea in a draft privacy report in December 2010.
Some of the browser providers including Mozilla’s Firefox, Apple’s Safari and Microsoft’s Internet Explorer have begun including a do-not-track choice in their browsers. But it is unclear how websites will respond to these do-not-track requests."