Do Not Track is an HTTP header signal introduced in 2009 as an industry-voluntary mechanism for users to communicate a preference not to be tracked.
Unlike the Global Privacy Control (GPC), which has legal force under the CCPA in California, DNT remains entirely voluntary. There is no US federal law requiring websites to honor it.
The result has been limited adoption. Major advertising platforms, analytics providers, and social networks largely ignore DNT signals, citing the lack of legal obligation and definitional ambiguity around what 'tracking' means.
DNT has been superseded in practical and regulatory significance by GPC, which California and Colorado have recognized as a legally-valid opt-out signal under their respective privacy laws. For organizations navigating consent signals, GPC now deserves more compliance attention than DNT.