An avid PhoneDog reader asked me last week:  "What is a smartphone, anyway?  You mention them in your reviews, but I'm not really sure what makes one phone smart and another ... not smart?"

Good question.  I had a pretty solid working definition of my own but did some research before putting fingers to keyboard.  I've included links to a few other helpful definitions below, but here's what I came up with:

A Smartphone is essentially a scaled-down personal computer that combines  communications - including cell phone functionality - and personal data management features in a mobile device.  While more and more current "non-smart" phones feature smartphone-esque features such as calendar and email applications, these key points separate smartphones from the pack:

1. An operating system that supports user-installable applications not necessarily approved by the manufacturer or service provider. 
   There are literally thousands of commercial and free/shareware apps available for smartphone operating systems.  While non-smartphones often support the download and installation of games and other programs (usually Java-based), these programs are usually approved by and sold through network operators.  Smartphone OSs more readily allow for applications to be independently developed, distributed and installed.
2. Robust communications and organization applications often including: 
   - Integrated synching of email and calendar/contacts information with a personal computer and enterprise server
   - Full HTML Web browsing and Email, and support for Email attachments
   - Applications for viewing and/or editing popular file formats including MS Word, Excel, and PowerPoint
3. Advanced methods for data input and navigation, particularly when it comes to entering text. 
   Usually this means a touchscreen and/or full QWERTY keypad, and often also includes a side-mounted thumbwheel or other shortcut buttons beyond what's found on "consumer" level phones

Examples of current smartphones include basically anything that runs the Windows Mobile, BlackBerry, Palm, or Symbian (Series 60/80 or UIQ) operating systems.  Popular smartphones right now include the BlackBerry Curve and Pearl. HTC Dash , Wing, and Mogul (Windows Mobile), Palm Treo Series, and Nokia E61 and E70 (Series 60) and Sony Ericsson p990 and p1i (UIQ).

You're probably thinking something like, "Wait, my phone lets me install software," or "My phone has a QWERTY keypad," but didn't think of your handset as a smartphone.  Well, the line between smart- and non-smartphones has definitely blurred over the past few years, particularly as SMS messaging and mobile email have gained in popularity. 

Consumer messaging phones like the LG enV for Verizon, Samsung u740 for Verizon and "Blast" for T-Mobile, and Nokia 6800/6820 feature full QWERTY keyboards but aren't really smartphones.    Advanced messaging phones like the new Helio Ocean and Apple iPhone feature a QWERTY board and touchscreen, respectively,  and both combine robust Web and Email functionality.  But limited third-party software development and corporate synch options have folks wondering if either is really a "smartphone."

More articles can be from the following links: Smartphone definition, or What is a Smartphone.