Microsoft has brought Cortana digital assistant to Windows 10. It will be right beside the Start button of the Windows 10 as a form of a search box.
You can use Cortana to perform searches, launch apps, check flight statuses, weather, set alarms, make Skype calls and send emails etc. The results will pop up above the Cortana search box, as you can see in this screenshot:
Here's a screenshot of file search:
On smaller devices (tablet and smartphones), rather than popping up from the task bar, Cortana takes up the entire screen:
Screenshots from The Verge