Worries over Internet privacy have spurred lawsuits, conspiracy theories and consumer anxiety as marketers and others invent new ways to track computer users on the Internet. But the alarmists have not seen anything yet.

In the next few years, a powerful new suite of capabilities will become available to Web developers that could give marketers and advertisers access to many more details about computer users’ online activities. Nearly everyone who uses the Internet will face the privacy risks that come with those capabilities, which are an integral part of the Web language that will soon power the Internet: HTML 5.

The new Web code, the fifth version of Hypertext Markup Language used to create Web pages, is already in limited use, and it promises to usher in a new era of Internet browsing within the next few years. It will make it easier for users to view multimedia content without downloading extra software; check e-mail offline; or find a favorite restaurant or shop on a smartphone.

Most users will clearly welcome the additional features that come with the new Web language.

“It’s going to change everything about the Internet and the way we use it today,” said James Cox, 27, a freelance consultant and software developer at Smokeclouds, a New York City start-up company. “It’s not just HTML 5. It’s the new Web.”