Windows Phone 8.1

Windows Phone 8.1, rolled out at Microsoft's Build Conference in San Francisco, California, on April 2, 2014, is the third generation of Microsoft's Windows Phone mobile operating system, succeeding Windows Phone 8.It was released in final form to Windows Phone developers on April 14, 2014 and reached general availability on July 15, 2014.All Windows Phones running Windows Phone 8 will be upgraded to Windows Phone 8.1 with release dependent on carrier rollout dates.

Windows Phone 8.1 is also the last version that will be under the Windows Phone brand name and will be succeeded by Windows 10 Mobile. Some Windows Phone 8.1 devices are capable of being upgraded to Windows 10 Mobile. Microsoft delayed the upgrade and reduced the supported device list from their initial promise.

  

 First Windows Phone 8.1 Mobile of Manufactured By Microsoft is Lumia 535.

 HTC ONE M8 WINDOWS PHONE VER.

Nokia Lumia 930

Cortana.

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).
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.

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.

 Cortana on Windows Phone 8.1 Mobile

This feature, which is currently in beta, was released in the United States in the first half of 2014 and in China, the United Kingdom, India, Canada and Australia in August 2014. It will be publicly available in most other countries by late 2014 or early 2015.
Microsoft has committed to updating Cortana twice a month and add features. The new features may include more "easter egg" replies, improvements in UI and better voice modulations.

  Windows Phone 8.1's Action Center

 A customized Windows Phone 8.1 Start Screen.