Do Not Track is a standard being developed by W3C, which allows a user to send an http header requesting that the end website does not track them. The exact scope and meaning of Do Not Track is currently being debated. Meanwhile, very few companies have agreed to respect it.
Do Not Track is available and implemented in a number of web browsers, including current versions of Firefox, Internet Explorer and Safari. Currently, in each case, it has to be activated by the user, so would not answer a requirement for prior consent, nor will setting it one place set it across all applications on a device. Many websites include content from third party websites. This third party content is usually advertisements. Third party content does not only advertise on the first party’s website, the presence of the third party’s advert on the website the user is viewing means that the website will be sending information about the user back to that third party, enabling them to build up a profile for that user without the users knowledge or permission.
Two technologies being developed to protect user privacy from behavioural tracking are Tracking Protection Lists, proposed by Microsoft, and Do Not Track, developed by Mozilla. Tracking Protection Lists can be created by a user to accept or decline a third party’s ability to track or monitor a user’s browsing habits. There are a number of problems with TPLs. They cannot provide absolute protection or privacy and, although they can be suggested by the Internet provider, it would be the responsibility of the individual user to monitor and update their own TPL which is not an easy task. The use of a tracking protection list presumes that the user has some prior knowledge of third party tracking in order for that user to know, and compile a list of what they would like to allow or block. The user must also trust the list providers, as it is not easy to verify whether third party sites are actually being blocked or not. Do Not Track is a simpler way that users can opt out of being tracked by third parties. Many third parties do not currently offer this Do Not Track option. DNT does not have to be monitored and updated by the user like TPLs. It is a one off opt out option that will send this Do Not Track message to all third party websites. Do Not Track and Tracking Protection Lists are not mutually exclusive. They can be used in conjunction with each other to provide a higher level of privacy. However, it is unclear whether TPLs and DNT actually prevent third parties from tracking the browsing behaviour of a user, or if opting in to DNT or creating a TPL merely prevents third parties using the gathered information to target advertisements at the user.