A personal digital assistant (PDA) is a portable electronic device used for personal organization and communication. PDAs usually feature touch screens for input with a finger or stylus, memory cards for removable storage, organizational software such as a calendar and address book, and means to interface with a personal computer, either through a cable or using a wireless protocol such as Bluetooth®. Most include the capability to add applications, such as business software or games.
There are a broad range of PDAs, bridging the gap between cellular phones and laptop computers in terms of both size and functionality. They are usually small enough to be conveniently carried in a pocket or belt clip. One that includes cell phone capability is known as a smartphone, and these are far and away the most popular category of PDAs on the market.
The ability to replace a number of bulky paper organizational tools with a single convenient device is a main selling point for PDAs. The term "personal information manager" (PIM) is used to refer to a software suite used for personal organization. Such a suite is usually included with a personal digital assistant, though some PIMs run on personal computers or other platforms. This software typically includes a calendar, address book, note pad, calculator, to-do list, and other small applications mirroring those found in a paper-based personal organizer. More sophisticated bundles may also include word processing and spreadsheet software. The term "Personal Information Manager" was also used to refer to PDAs themselves early in the history of the device class.
A number of operating systems (OS), called mobile operating systems, have been created specifically for PDAs. Many mobile operating systems are based on familiar computer operating systems — such as Microsoft Windows®, Mac OS®, or Linux® — that have been heavily modified to run using a mobile device's limited hardware and interface elements. Others are built from scratch with the electronic device in mind.
While the PC market has historically been dominated by Windows®, no single OS holds a clear majority in the mobile market. When personal digital assistants rose to popularity in the late 1990s and early 2000s, many popular devices by Handspring™ and Palm®, Inc. ran Palm OS®, which featured a simple interface and primitive handwriting recognition software called Graffiti™. With the introduction of the Palm Pre™, the operating system was succeeded by Palm webOS™. Microsoft's mobile OS is called Windows Mobile®; Apple's is called iPhone® OS. Symbian™ OS and the Google-initiated Android™ are other mobile operating systems.
The rapid rise to popularity of the personal digital assistant, coupled with its early association as a business-class status symbol, inspired a small popular culture backlash. Self-help writer Merlin Mann created the tongue-in-cheek Hipster PDA, which is a pack of index cards held together with binder clips, accompanied by a ballpoint pen. The idea has caught on with a certain segment of the population, and a community of users has risen to provide support for the "device."