Windows Phone is a proprietary mobile operating system developed by Microsoft. Windows Phone introduced a new design language, previously called Metro UI, but later renamed to simply Modern.
Microsoft licenses the software to third-party hardware manufacturers, but keeps a stringent list of minimum requirements for the hardware it runs on to ensure the best user experience.
In 2011 Nokia announced it has chosen Windows Phone as the OS for all its future smartphones providing a solid backing for the fledgling OS and in the same time betting all of its mobile phone business on its success.
Windows Phone 7
The initial announcement of Windows Phone 7 came in February, 2010. It was later launched in October the same year.
Windows Phone 7.5 Mango
The next major update – Windows Phone 7.5 Mango – saw the light of day in May 2011. The update brought the frequently requested multi-tasking for third-party apps and added the updated Internet Explorer 9, Twitter integration and Windows Live SkyDrive access.
Windows Phone 7.5 Tango
Another update followed in 2012, dubbed Tango, which lowered the minimum hardware requirements for the smartphones essentially allowing Windows Phones at lower price points. Other new features include the capability to create a Wi-Fi hotspot and flip-to-silence.
Windows Phone 7.8
Reportedly, a Windows Phone 7.8 update is in the works. It should carry over some of the new features of Windows Phone 8 down to the lineup of previous smartphones, as those would not be updated to Windows 8.
The launch schedule is yet unannounced by Microsoft.
Windows Phone 8
In October 2012 Microsoft released a major update to the mobile OS. Older devices are denied an update.
Windows 8 introduced much awaited features such as multi-core processor and multiple screen resolution support, removable memory card support, USB Mass storage mode, DivX/XviD video playback support, NFC support, Bluetooth file transfers, Kid's Corner, etc.
The new release also replaced the Windows CE-based architecture to a Windows NT kernel, allowing easy applications porting from the desktop Windows 8 to the mobile one, mainly benefiting the tablets running the new Windows 8 RT.