<P> The Windows Phone software updates delivered through "Preview for Developers" are complete, finished versions of the OS, as opposed to the Windows 10 Mobile builds in the Windows Insider program, which are preview versions of the software that are intended for users to try out new features before the final release and may contain bugs . </P> <P> Windows Phone 8.1 introduces a host of notable new features, most of which were unveiled in a preview released to developers on February 10 . </P> <P> Cortana is a personal virtual assistant that was added in Windows Phone 8.1, and is similar to Google Now and Apple's Siri . The Cortana name derives from the Halo video game series, which is a Microsoft franchise exclusive to Xbox and Windows . Cortana's features include being able to set reminders, recognize natural voice without the user having to input a predefined series of commands and answer questions using information from Bing (like current weather and traffic conditions, sports scores, and biographies). </P> <P> Cortana also uses a special feature called a "Notebook", where it will automatically gather information about and interests of the user based on usage and allow the user to input additional personal information, such as quiet hours and close friends who are allowed to get through to the user during these quiet hours . Users can also delete information from the "Notebook" if they deem it undesirable for Cortana to know . </P>

Name of the windows phone 8.1 virtual assistant