iCloud Tabs let you quickly and easily access web pages that you've already opened in Safari on your other Apple devices, be they other iPhones, iPod touches, iPads, or Macs. That's right, any and every other Apple device you own, if it's logged into iCloud with the same Apple ID, will automatically share its tabs with every other device. (Tabs created in Private Browsing mode are excluded, of course - Apple doesn't judge!) While this isn't a new feature, and works pretty much the same on Mac and iPad as it did previously, for iPhone and iPod touch, the way you access iCloud Tabs has changed in iOS 7. Here's how it's done now!
iCloud Tabs allow you to access web pages you have open in Safari across any iPhone, iPad, or Mac you've got synced up with your iCloud account. If you're at home browsing on your Mac and later need to access a page you had open on that Mac from your iPhone or iPad, there's no need to scour the web for it, just use iCloud Tabs to instantly view the page on any of your iCloud enabled devices.
Safari has been on the iPhone since the first version launched in 2007, and has been steadily improved, year after year, version after version, ever since. iOS 6 follows the same, steady, evolutionary pattern, addressing long standing user pain-points like image uploads, and providing parity with features from other browsers, like Chrome's tab sync. It also makes Reading List more robust, and provides an interesting way for websites to alert users about, and move them into, apps.