Cortana

Cortana is an intelligent personal assistant created by Microsoft for

 Windows Phone 8.1 and Windows 10 Mobile (where it now supersedes

 Bing Mobile),^[4] Microsoft Band, Xbox One^[5][6] Windows 10,^[7] and

 coming to iOS, Android,.

Cortana was demonstrated for the first time at the Microsoft BUILD

 Developer Conference (April 2–4, 2014) in San Francisco.^[1] It has

 been launched as a key ingredient of Microsoft's planned "makeover"

 of the future operating systemsfor Windows Phone and Windows.^[4] It

 is named after Cortana,^[9] a synthetic intelligence character in

 Microsoft's Halovideo game franchise originating in Bungie folklore,

 with Jen Taylor, the character's voice actress, returning to voice the 

personal assistant's US-specific version.^[11]

Cortana is currently available in English, French, German, Italian,

 Spanish, Chinese, and Japanese language editions, depending

 on the software platform and region in which it is used.

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).^[17][18][19] Windows 8.1's universal Bing SmartSearch

 features are incorporated into Cortana, which replaces the previous

 Bing Search app which is activated when a user presses the "Search"

 button on their device.^[20] Cortana also includes a music recognition

 service.^[21] Cortana can also roll dice and flip a coin by asking the

 commands "roll a dice" (one dice), "roll the dice" (two dice), and "flip a coin"

,^[22] Concert Watch is a feature that helps Cortana determine which bands

 or musicians you are interested in by monitoring your Bing searches.^[23]

 Cortana also integrates with the Microsoft Band for Windows Phone

 devices if connected via bluetooth.^[24][25] On the Microsoft Band

 Cortana can make reminders and bring phone notifications.^[26]

Since the Lumia Denim series, launched in October 2014, active listening

 was added to Cortana, enabling it to be triggered with the phrase: “Hey Cortana,”

 even across the room and without the need to touch the phone. After the trigger

 phrase is spoken, Cortana can be controlled normally for tasks like setting a

 reminder, asking a question, or launching an app.^[27] Some devices

 from the United Kingdom by O2 have received the Lumia Denim update

 without the feature but this was later clarified as a bug and Microsoft had

 since fixed it.^[28]

Cortana also integrates with services like Foursquare to provide restaurant 

and local attraction recommendations.

Thus it is very sad thing that Cortana is only available on windows phone and

 windows 10, no one can download it for other platform!!