Handheld computers—also known as personal digital assistants (PDAs)—are small, portable devices that offer users many of the same features and capabilities as desktop computers at a fraction of the size. Although the terms "handheld computer" and "PDA" are often used interchangeably, handhelds tend to be larger and feature miniature keyboards, while PDAs tend to be smaller and rely on a touch screen and stylus for data entry.

Since their introduction in the late 1990s, hand-held computers have become standard equipment for many professionals, providing them with tiny, versatile electronic alternatives to paper day planners. "Once the domain of early adopting gadget lovers, handhelds now organize and update millions of mobile business professionals," reports Mike Brown at HandheldComputerDepot.com. Users have found PDAs to be particularly helpful tools for organizing and maintaining personal data, such as address books, appointment calendars, project lists, and expense reports...