[$] The sad, slow-motion death of Do Not Track

"Do Not Track" (DNT) is a simple HTTP header that a browser can send tosignal to a web site that the user does not want to be tracked. The DNTheader had a promising start and the support of major browsers almost a decadeago. Most web browsers still support sending it, but in 2020 it is almostuseless because the vast majority of web sites ignore it. Advertisingcompanies, in particular, argued that its legal status was unclear, andthat it was difficult to determine how to interpret the header. There havebeen some relatively recent attempts at legislation to enforce honoring theDNT header, but those efforts do not appear to be going anywhere. Incomparison, the European Union's GeneralData Protection Regulation (GDPR) and the CaliforniaConsumer Privacy Act (CCPA) attempt to solve some of the same problemsas DNT but are legally enforceable.