So what is Windows Mobile? This is straight from Wikipedia
Windows Mobile is a compact operating system combined with a suite of basic applications for mobile devices based on the MicrosoftWin32 API. Devices that run Windows Mobile include Pocket PCs, Smartphones, Portable Media Centers, and on-board computers for certain automobiles. It is designed to be somewhat similar to desktop versions of Windows, feature-wise and aesthetically. Additionally, third-party software development is available for Windows Mobile. Originally appearing as the Pocket PC 2000 operating system, Windows Mobile has been updated multiple times, with the current version being Windows Mobile 6.5.
Microsoft projected in 2008 that shipments of devices with Windows Mobile will increase from 11 million to 20 million units, but it missed its initial goal in only selling 18 million licenses citing the delayed launch of certain smartphones. Windows Mobile’s market share as an operating system for smartphones worldwide has fallen from 23% in 2004 down to 12% in 2008. Windows Mobile now has a worldwide smartphone market share of 14%. Microsoft licenses Windows Mobile to four out of the world’s five largest mobile phone manufacturers, with Nokia being the other. Some current estimates suggest that 80% of the 50 million Windows Mobile devices made have been built by one contract manufacturing group, HTC, which makes handsets as for several major companies under their brands, as well as under its own brand. However, in February 2009 Microsoft signed a deal with the third largest mobile phone maker, LG Electronics, to license Windows Mobile on 50 upcoming LG smartphone models.