Apple Inc. has added a do-not-track privacy tool to a test version of its latest Web browser for keeping customers' online activities from being monitored by marketers.

The tool is included within the latest test release of Lion, a version of Apple's Mac OS X operating system that is currently available only to developers. The final version of the operating system is scheduled to be released to the public this summer. Mentions of the do-not-track feature in Apple's Safari browser began to appear recently in online discussion...