Windows Mobile

Windows Mobile is Microsoft's operating system that powers newer handheld PDAs and mobile phones. This operating system from Microsoft includes a host of features, such as a web browser, email application, media player, diary, address book and a whole load of other useful applications.
There are two key versions of the Windows Mobile Operating system:
Windows Mobile , Pocket PC - Desdigned for PDAs and mobile phones with touchscreen
Windows Mobile, Smartphone Edition - Desgined for mobile phones. No touchscreen

This page also has a lot more useful information about Windows Mobile

Source: http://www.filesaveas.com/windowsmobile.html