Over the weekend, a new build of Windows 10 leaked and with it came with upgraded apps; Spartan has received a few new features too. If you need to open a link with Internet Explorer, that functionality is now built into the new browser.
This feature is a bit of an odd addition to the browser as Microsoft is making a big deal about how Spartan is the future of web browsing and yet they have included a shortcut to fire up their older browser. It's understandable why someone might want this feature if the page is not rendering in Spartan correctly but it goes to show that even Microsoft is having trouble of truly shaking off Internet Explorer.
This feature will most likely be used in the corporate setting where legacy pages will not load correctly in Spartan but for the consumer, if Microsoft plays its cards right, the feature should rarely, if ever, be used.
To open links with Internet Explorer, if you click on the Settings icon in the top right, you can then open the page in Internet Explorer (shown above). After you do open a page with IE, Microsoft does prompt you with a survey to explain why you needed the other browser so that they can work to improve Spartan.
Think of this feature as a security blanket for the browser to make sure that it has all scenarios covered as they build out the modified Trident engine.
Source : neowin