iCloud Tabs is a new Safari feature in iOS 6 and OS X Mountain Lion, that sync your open tabs in Safari across all your iCloud enabled devices. It’s a rather seamless implementation, allowing you to start browsing on one device and pick up right where you left off.
To access iCloud Tabs on iOS 6, tap the Bookmarks button in Safari. On the Bookmarks menu, tap on the “iCloud Tabs”. This will list all open tabs in Safari for all your other iOS devices and Macs. Tap on the item to continue reading what you left off.
On OS X Mountain Lion, click on the iCloud icon at the left corner toolbar of Safari to access your iCloud Tabs.
To disable open tabs in Safari from being sync to iCloud on one device or Mac, enable Private Browsing on the device or Mac. To enable Private Browsing in iOS 6, open Settings > Safari and turn on the “Private Browsing” switch. To enable Private Browsing in OS X Mountain Lion, select from Safari menu Safari > Private Browsing.
To disable iCloud Tabs feature totally, just turn off the Safari switch in iCloud settings. Under iOS 6, iCloud settings is at Settings > iCloud. For OS X Mountain Lion, open System Preferences to access the iCloud settings.