Cortana is a virtual assistant bundled with Windows 10. In the production branch of the OS, Cortana is integrated with the Search feature on the taskbar. Microsoft is considering detaching Cortana from the taskbar and moving it to the Action Center.
Microsoft is going to add a floating search box to Windows 10 version 1803 "Redstone 4". It is powered by Cortana and replaces the search box in the taskbar. The test version of the feature is already available in the recently released Windows 10 build 17040 Insider Preview.