Do Not Track is designed to help protect Web users from unwanted tracking by online ad companies and site operators. In practice, the standard is implemented as a header that users browsers send to sites expressing their DNT preferences. Sites that adopt DNT essentially pledge not to track or record visitors interactions with the site. The new proposed standard put forth by the EFF and its allies is meant to improve on the existing policy, thought it s still a voluntary policy. One of the main issues standing in the way of the current DNT standard is resistance from the ad industry.
Source: https://threatpost.com/eff-adblock-and-others-launch-new-do-not-track-standard/114121/