Worries over Internet privacy have spurred lawsuits and consumer anxiety as marketers invent new ways to track computer users on the Internet. But the alarmists have not seen anything yet. But in the next few years, a powerful new suite of capabilities will become available to web developers that could give marketers access to many more details about computer users' online activities. The new code, the fifth version of Hypertext Mark-up Language (HTML5) used to create web pages, is already in limited use, and it promises to usher...