By JULIA ANGWIN and EMILY STEEL

As the surreptitious tracking of Internet users becomes more aggressive and widespread, tiny start-ups and technology giants alike are pushing a new product: privacy.

Companies including Microsoft Corp., McAfee Inc.—and even some online-tracking companies themselves—are rolling out new ways to protect users from having their movements monitored online. Some are going further and starting to pay people a commission every time their personal details are used by marketing companies.

"Data is a new form of currency," says Shane Green, chief executive of a Washington start-up, Personal Inc., which has raised $7.6 million for a business that aims to help people profit from providing their personal information to advertisers.

The Wall Street Journal's year-long What They Know investigation into online tracking has exposed a fast-growing network of hundreds of companies that collect highly personal details about Internet users—their online activities, political views, health worries, shopping habits, financial situations and even, in some cases, their real names—to feed the $26 billion U.S. online-advertising industry...

Read the full article on The Wall Street Journal