Pocket PC can mean an operating environment based on Microsofts Windows CE operating system (a variation of Microsoft Windows operating system for miniature computers and embedded systems) or a handheld device that runs a specific version of that OS. According to Microsoft, the Pocket PC is ""a handheld device that enables users to store and retrieve e-mail, contacts, appointments, play multimedia files, games, exchange text messages with MSN Messenger, browse the Web, and more.

To be labeled as a Pocket PC, there are some prerequisites for handheld devices, such as running Microsoft Windows CE, PocketPC edition; being bundled with a specific suite of applications in ROM that include a touchscreen, directional pad, and a set of hardware application buttons; and being based on a ARM version 4 compatible CPU, Intel XScale CPU, MIPS CPU, or SH3 CPU.

The Pocket PC platform was introduced in 2000, by Microsoft and includes a combination of Windows CE Version 3.0, an enhanced user interface, Pocket Office applications, handwriting recognition, an e-book reader, wireless Internet, etc. Versions that include mobile phone features and capabilities, such as Mobile 2003 Phone Edition, have also been released. Popular handheld PDAs such as the Hewlett-Packard Jornada 540 series, the Compaq iPaq, and the Casio Cassiopeia E-115 run on the Pocket PC platform.

The latest Pocket PC from Microsoft is Windows Mobile 5.0, officially released on May 10, 2005. It is based on Windows CE 5.0, can be mounted as a USB Mass Storage device, and incorporates features such as Direct3D Mobile, integrated Bluetooth and Wi-Fi stacks. A Phone application is also included, and Windows Mobile 5.0 is compatible with Microsoft's Smartphone OS and related applications.