A fifth of all Americans with cellphones say they primarily surf the Web using mobile devices — not a desktop or laptop, according to the Pew Research Center. That's consistent with a Morgan Stanley report that predicts the mobile Web will soon eclipse desktop browsing.
But mobile Internet browsing represents only a fraction of the other activity that happens on tablets and smartphones. According to Flurry, a company that helps advertisers track users' online behavior, 80 percent of U.S. consumers' mobile-device time is spent in apps. Just 20 percent is spent in a browser. Compared against all forms of browsing (desktop and mobile), we spend 30 percent more time in apps than we do surfing the Web.
That gives advertisers a compelling reason to expand in-app advertising. Yet according to Peter Swire, who helped lead industry negotiations on Do Not Track and who now sits on White House review panel on intelligence, the biggest focus in policy debates over Do Not Track has been on browsers. The current generation of Do Not Track technology, then, may not be effective at protecting users' privacy.
The Federal Trade Commission has signaled it wants to regulate advertising on mobile apps, as well as on browsers. In a nod to Apple, which let users of its iOS mobile platform turn off app-based tracking, the FTC proposed a "platform-level" version of Do Not Track. Such a system would mean users would not have to deny tracking on an app-by-app basis. Just hit one button, and you're free.
But the FTC likely won't act before Congress asks it to. Do Not Track proponents also suffered another setback last month when a key participant in the negotiations withdrew.
Stopping advertisers from tracking users as they browse the Web has proven to be a big enough challenge for privacy advocates. Now they'll have to figure out how to extend the Do Not Track concept to mobile devices, too.