PDAs (Personal Digital Assistants) are handheld computers that originally were designed as personal organizers, and they do this really well. The basic features of any PDA are a date book, address book, task list , and memo pad. While these features are very helpful at keeping someone organized, the feature that clinched their utility for any busy person who uses a desktop computer is that of easy synchronization of information with the desktop. For example, I can easily work on my desktop, make a new appointment and cut some directions out of an e-mail someone sent me and paste it into a memo using my PDA's desktop software. The next time I put the PDA in the cradle and synchronize, that new information ends up on my PDA.

There are three major PDA operating systems that are competing for the PDA market. Palm Computing, owned by 3Com, is the manufacturer of the original Pilot organizer and their Palm OS is the market leader in PDA sales. Palm has recently begun to license its operating system out to third-party manufacturers. Handspring, Qualcomm, and TRG have all now released PDA's based on Palm OS. Nokia and Sony are due to follow in the near future.

Several companies, including Compaq, Hewlett Packard, and Casio make the competing PDA's that run on Microsoft's Pocket PC operating system and are currently running second to the Palm OS in the PDA market. However, Microsoft seems committed to trying to improve their market share.

Symbian is a joint venture between Psion, Nokia, Ericsson and Motorola which has produced the EPOC operating system. This is currently in use on PDA's produced by Psion, Ericsson and Oregon Scientific. EPOC remains the most popular PDA operating system in Europe where its ability to handle mobile communications is a particular asset.