In May, Microsoft announced that DNT would be on in IE10, a position that has raised hackles among online advertisers, who have balked at browsers that turn on DNT by default.

Windows 8 tells users that Do Not Track is turned on when they choose the "Express settings" option.

Advertisers, browser makers, privacy advocates and others -- working in a Worldwide Web Consortium (W3C) standards-setting group -- have struggled to agree on DNT's implementation. Some parties, including Mozilla, the creator of Firefox, have argued that users must to engage DNT for the signal to count, and thus reject Microsoft's by-default approach.

If users choose "Customize," they can toggle off Do Not Track during Windows 8's setup process.

European Union privacy officials sided with Microsoft in the on-by-default controversy when in June they in IE10. The EU suggested the standards group accept a "first-run" option, meaning the setting would be acknowledged when a browser or OS was launched for the first time.