Cortana was demonstrated for the first time at the Microsoft BUILD Developer Conference (April 2–4, 2014) in San Francisco. It has been launched as a key ingredient of Microsoft’s planned “makeover” of the future operating systems for Windows Phone and Windows. It is named after Cortana, a synthetic intelligence character in Microsoft’s Halo video game franchise originating in Bungie folklore, with Jen Taylor, the character’s voice actress, returning to voice the personal assistant’s US-specific version.
As of 2015, Cortana is available as a beta to all users of Windows Phone 8.1 in the United States (US English), China (Mandarin Chinese), and the United Kingdom (UK English). Users in certain countries can also choose to opt-in to the alpha for the English, francês, alemão, italiano, and Spanish versions of Cortana on Windows Phone as of August 2014. In most of these regions, Cortana is also available via Windows Insider to both PC and mobile preview users of Windows 10.