A discontinued browser setting that attempted to give users a simple, universal way to opt out of third-party tracking across the web. Introduced around 2009 and implemented in major browsers in the years that followed, Do Not Track (DNT) added a small header to each request telling websites and ad networks that the user did not consent to behavioral tracking. The idea aligned with the rising demand for transparency and user control, and for a brief period, it looked like it might become a meaningful standard.
History and Purpose
DNT was designed to allow Internet users to opt out of tracking by websites, which includes the collection of data regarding a user's activity across multiple distinct contexts, and the retention, use, or sharing of data derived from that activity outside the context in which it occurred. The header was originally proposed in 2009 and was adopted by most major browsers within a few years.
Failure and Decline
The initiative ultimately failed because it relied entirely on voluntary compliance. Without a legal mandate or industry-wide agreement, most advertisers, analytics providers, and publishers ignored the header. Even organizations that initially supported the concept found themselves at a competitive disadvantage if others refused to honor it. By 2019, the World Wide Web Consortium formally ended its standardization efforts, and browser vendors began phasing the feature out.
Legacy
Although DNT never achieved its intended impact, it played an essential role in advancing stronger, enforceable privacy signals and regulatory frameworks. As of 2025, some browsers had removed the header, including Apple Safari and Mozilla Firefox. Following the failure of the DNT initiative, a coalition of US-based Internet companies began working on alternative solutions to address user privacy concerns.