A PDA or Multifunction Mobile Device is a term for any small mobile hand held device that provides computing and information storage retrieval capabilities that can function as a cellular phone, fax sender, email reader, and personal organizer often with built in digital cameras and WiFi capabilities. These devices are often called PDA, Smartphone, Palmtops or Pocket PC.
Many of these devices now provide the ability to access web content remotely, over wireless networks. Depending on the device, these tools can either display native HTML web content, or re-purpose web content into the WAP (Wireless Application Protocol) mark up language, stripping the "web pages" of all imagery, but transmitting the text portion.
There are many types of PDAs broken down into a few basic categories. We have traditional PDAs and smart phones. Today's traditional PDAs are descendents of the original PalmPilot and Microsoft Handheld PC devices. Palm devices run the Palm OS (operating system), and Microsoft Pocket PCs run Windows Mobile, while the Blackberry use there own OS. The differences between the two systems are fewer than in the past.