The story of Cortana, Microsoft's Siri killer | The Verge

From an extensive overview

"Technically, Cortana isn’t supposed to exist for at least another 500 years, but that’s not stopping Microsoft from bringing her to life this week. While Apple has Siri and Google has Google Now — both digital assistants that run on smartphones — Microsoft is taking an approach that mixes the best of the competition with its own unique take. Based on a 26th-century artificially intelligent character in the Halo video game series, Cortana will debut as part of Windows Phone 8.1, the next big update for Microsoft’s mobile operating system."

The story of Cortana, Microsoft's Siri killer | The Verge