Windows Phone 8 is the second generation proprietary mobile operating system released on Oct 29th, codenamed "Apollo", developed by Microsoft featuring a new interface known as Metro or Modern UI.

Windows Phone 8 replaces it's CE-based architecture used on Windows Phone 7 devices with the Windows NT kernel found on many Windows 8 components. Current Windows Phone 7.x devices cannot run or update to Windows Phone 8 and new applications compiled specifically for Windows Phone 8 are not made available for Windows Phone 7.x devices.

Nokia announced a partnership with Microsoft on February 11, 2011 making Windows Phone 8 the primary operating system for Nokia.  However at launch, Windows 8 devices have also been manufactured by Samsung, HTC and Huawei.

Unveiling

On June 20, 2012, Microsoft unveiled Windows Phone 8 (codenamed Apollo), a second generation of the Windows Phone operating system for release later in 2012. Windows Phone 8 replaces its previously Windows CE-based architecture with one based on the Windows NT kernel with many components shared with Windows 8, allowing applications to be easily ported between the two platforms.

Windows Phone 8 will also allow devices with larger screens (the 3 confirmed sizes are "WVGA 800x480 15:9","WXGA 1280x768 15:9","720p 1280x720 16:9" resolutions) and multi-core processors, NFC (which can primarily be used to share content and perform payments), backwards compatibility with Windows Phone 7 apps, improved support for removable storage (which now functions more similarly to how such storage is handled on Windows and Android), a redesigned home screen incorporating resizable tiles across the entire screen, Nokia Maps integration, a new Wallet hub (to integrate NFC payments, coupon websites such as Groupon, and loyalty cards), and "first-class" integration of VoIP applications into the core functions of the OS. Additionally, Windows Phone 8 will include more features aimed at the enterprise market, such as device management, BitLocker encryption, and the ability to create a private Marketplace to distribute apps to employees—features expected to meet or exceed the enterprise capabilities of the previous Windows Mobile platform. Additionally, Windows Phone 8 will support over-the-air updates, and all Windows Phone 8 devices will receive software support for at least 18 months after their release.

In the interest of ensuring it is released with devices designed to take advantage of its new features, Windows Phone 8 will not be made available as an update for existing Windows Phone 7 devices. However, a future update, Windows Phone 7.8 will backport the redesigned home screen.

The following features were confirmed at Microsoft's 'sneak peek' at Windows Phone on June 20, 2012 and the unveiling of Windows Phone 8 on October 29, 2012.

Core

Windows Phone 8 is the first mobile OS from Microsoft to use the Windows NT kernel, which is the same kernel that runs Windows 8. The operating system adds improved file system, drivers, network stack, security components, media and graphics support. Using the NT kernel, Windows Phone can now support multi-core CPUs of up to 64 cores, as well as 1280x720 and 1280x768 resolutions, in addition to the base 800x480 resolution already available on Windows Phone 7. Furthermore, Windows Phone 8 also adds support for MicroSD cards, which are commonly used to add extra storage to phones.

Due to the switch to the NT kernel, Windows Phone 8 also supports native 128-bit Bitlocker encryption and Secure Boot. Windows Phone 8 also supports NTFS file system due to this switch.

Web

Internet Explorer 10 is the default browser in Windows Phone 8, and carries over key improvements also found in the desktop version.

Multitasking

Instead of the card-based multitasking utilized in Windows Phone 7, Windows Phone 8 includes true background multitasking. Multitasking is still invoked by pressing the "Back" key available on all Windows Phone devices.

Kids Corner

Windows Phone 8 adds Kids Corner, which operates as a kind of "guest mode". When Kids Corner is activated, apps and games installed on the device can be played or accessed without touching the data of the main user signed in to the Windows Phone.

Rooms

Rooms is a feature added specifically for group messaging and communication. Using Rooms, users can contact and see Facebook and Twitter updates only from members of the group created.

Data Sense

As an exclusive feature to Verizon Windows Phones, Data Sense allows users to set data usage limits based on their individual plan. DataSense can restrict background data when the user is near their set limit. A heart icon is used to notify the user when background tasks are being automatically stopped.

NFC and Wallet

Select Windows Phones running Windows Phone 8 add NFC capability, which allows for data transfer between two Windows Phone devices, or between a Windows Phone device, and a Windows 8 computer or tablet, using a feature called "Tap and Send".

In certain markets, NFC support on Windows Phone 8 can also be used to conduct in-person transactions through credit and debit cards stored on the phone through the Wallet application. Carriers may activate the NFC feature through SIM or integrated phone hardware. Orange will be first carrier to support NFC on Windows Phone 8. Besides NFC support for transactions, Wallet can also be used to store credit cards in order to make Windows Phone Store and other in-app purchases (which is also a new feature), and can be used to store coupons and loyalty cards.

Nokia Maps

Nokia Maps, which is based on Navteq, replaces Bing Maps as the standard mapping application for all devices running Windows Phone 8, as opposed to only Nokia devices in Windows Phone 7. All devices also have access to Nokia Drive, which includes turn-by-turn directions for navigation, and the ability to save maps for offline use.

Other Features

Xbox SmartGlass allows control of an Xbox 360 with a phone (Available for Windows Phone, iOS and Android)

Xbox Music services support playback audio files in Windows Phone, as well as music purchases.

Xbox Video services support playback of video files in Windows Phone but not video purchases.

Easy transfers

Native code support (C and C++), allows for simplified porting from platforms such as Android, Symbian, and iOS

Simplified porting of Windows 8 apps to Windows Phone 8 (compatibility with Windows 8 "Modern UI" apps)

Remote device management of Windows Phone similar to management of Windows PCs

VoIP and video chat integration for any VoIP or video chat app (integrates into the phone dialer, people hub)

Firmware over the air for Windows Phone updates

Minimum 18 month support of Windows Phone updates to Windows Phone 8 devices

Camera app now supports "lenses", which allow third parties to skin and add features to camera interface

Native screen capture is added by pressing home and power buttons simultaneously

Hebrew language support is added for Microsoft to introduce Windows Phone to the Israeli market.

Hardware Requirements

Windows Phone App

The Windows Phone app succeeds Zune Software as a sync application to transfer documents, music, videos, and other files between Windows Phone 8 and a Windows computer or tablet. A version for Mac OSX computers is also available.

Reported problems

• Wi-Fi connection is lost when the phone is locked. Microsoft has acknowledged the issue and said that a fix is coming soon.
• Windows Phone 8 users are reporting random reboots and freezes while in use.Microsoft planned to release an OTA update for this issue as soon as possible.
• Battery issues have been reported that seem to be fixed by disabling the tap + send (NFC) feature.
• Many users are reporting Bluetooth pairing issues with car Bluetooth systems
• Videos larger than 4GB get corrupted when transferred to the computer.