Windows Mobile is a mobile operating system developed by Microsoft that was used in smartphones and mobile devices, but by 2011 was rarely supplied on new phones. The last version is "Windows Mobile 6.5.5"; it is superseded by Windows Phone, which does not run Windows Mobile software. Unlike operating systems for desktop computers, it is usually not possible to upgrade the operating system on a Microsoft based mobile phone via official and legal means, even by a later release of the same basic operating system let alone a different one; hardware replacement is the only way for less popular and older devices.
Windows Mobile is based on the Windows CE 5.2 kernel. and first appeared as the Pocket PC 2000 operating system. It is supplied with a suite of basic applications developed with the Microsoft Windows API, and is designed to have features and appearance somewhat similar to desktop versions of Windows. Third parties can develop software for Windows Mobile with no restrictions imposed by Microsoft. Some software applications can be purchased via the Windows Marketplace for Mobile. By 2011, much software is developed and maintained only for the newer Windows Phone; there is little development and support for the obsolescent Windows Mobile.
Most Windows Mobile devices come with a stylus, which is used to enter commands by tapping it on the screen. Microsoft announced a completely new phone platform, Windows Phone, at the Mobile World Congress in Barcelona on February 15, 2010. Phones running Windows Mobile 6.x will not be upgradeable to version 7, officially. Several developers however, have ported Windows Phone to devices natively running Windows Mobile, an example being the HTC HD2.
Windows Mobile's share of the smartphone market has fallen year-on-year, decreasing by 20% in Q3 2009. In August 2010, it was the fifth most popular smartphone operating system, with a 5% share of the worldwide smartphone market (after Symbian, BlackBerry OS, Android, and iOS).
