PDA is an Acronym for Personal Digital Assistants. It is an umbrella term for all small handheld computers typically operated via a touchscreen stylus rather than a keyboard. They're used to write notes, track appointments, store contacts information, and generally keep your life in order.

Their software typically includes embedded Email, calendaring, address book, tasks list, and memo applications. Third party and custom developed software can extend the functionality of these small devices.
A Pocket PC is a PDA that runs a variation of the operating system Windows CE. It has many capabilities of modern desktop PCs. It has a custom shell and a set of customized applications written by Microsoft but sold by OEMs such as Hewlett-Packard, Toshiba, Acer, O2 and others. Pocket PCs are certified by Microsoft to conform to a specific set of standards in both hardware and software. Some of these devices, running Microsoft Windows Mobile 2003 Phone Edition, also include mobile phone features. They can store and retrieve e-mail, contacts, appointments, play multimedia files, games, exchange text messages with MSN Messenger, browse the Web, and more. You can also exchange, or synchronize, information with a desktop computer.
Applications for the Windows Mobile-based Pocket PC feature a familiar interface and consistent functionality, so they're easy to learn and use right away. Pocket versions of popular Microsoft applications let you easily update and share the same data and documents that you have on your desktop such as mobile version of Microsoft Office Outlook 2002, Microsoft Pocket Word, Microsoft Pocket Excel, Microsoft Pocket Internet Explorer, Windows Media Player and many more.
Strictly speaking, palmOne is the name of the hardware division of the company formerly known as Palm, Inc. after the split of the hardware and software divisions and subsequent merger with Handspring, Inc. The software division of Palm, Inc. became known as PalmSource, Inc. and took over development and licensing of the Palm OS.
Known for its unique commitment to an elegant, simple interface that is easy to use, the palmOne product family is built for what matters to customers. Today, the product family consists of the Zire and Tungsten series handhelds and the Treo brand of smartphones, equipped with a comprehensive suite of Personal Information Management (PIM) software, infrared beaming capabilities, calculator, note-taking applications, and games. A range of additional features -- including hi-res color screens, wireless capabilities (Bluetooth, Wi-Fi, cellular), MP3 software and digital cameras -- ensures that there's a palmOne handheld or smartphone to meet almost any user's needs.
I take it that u are referring to
Palm devices when you ask what is palmOne. palmOne™ handhelds began as personal organizers, with a suite of applications that made people's lives easier. Today, you can create digital photo albums on a palmOne handheld, plug in a wine enthusiast expansion card 1 or add a portable keyboard 1 to create documents on the road. But no matter how much palmOne handhelds have evolved, they all still offer the "classic functions", namely:
- Infrared
"Beam" files & apps to other IR-enabled Palm OS® devices.
- Date Book
Keep track of app'ts, notes and deadlines.
- Address Book
Store, then retrieve #'s, names and addresses.
- Home
Find & launch software applications.
- Data Entry
Use graffiti or on-screen keyboard.
- Calculator
It's easy! Do the math.
- Find
Enter a name or a word and it appears.
- Memo Pad Note Pad
A thought? Jot it down on screen.
- To Do List
If it needs to get done, list it here.
- Peripheral Connector
Add optional peripherals such as GPS, modems or HotSync® cradle.
Starting with the original PalmPilot™; organizer, palmOne products have always been designed to keep people organized. But today, you can also
do a whole lot more.
I think the information should more than suffice your basic query above.
