You will notice an Import/Export area in the Options page of both Yahoo! Calendar and Yahoo! Address Book. Please note that there is also an Import and Export option in the Intellisync for Yahoo! program as well.

Anyone who has used import / export to keep data from multiple sources consistent knows the problems it can cause -- duplicate data and overwritten changes.

For example, let's say you want identical data in your Palm Pilot and your Yahoo! Address Book. While at home, you add John Doe to your Yahoo! Address Book and later you add Jane Smith to your Palm Pilot during a meeting. At the end of the day, you'd like to get the same information in both places.

So, you export your Palm Pilot data and import it into Yahoo! Address Book. You get Jane Smith in your Yahoo! Address Book but you also get duplicate entries for every other contact. To avoid this duplication problem, you could first delete all your Yahoo! Address Book data before importing the Palm Pilot data. But then, since it only existed in your Yahoo! Address Book, you would have lost John Doe's entry.

Synchronization solves these problems by taking changes to your data, regardless of where they were made, and distributing them to your selected PIM.

You will also notice an Import and Export feature in Intellisync. In the Intellisync for Yahoo! Configuration, you will find these after selecting the "Choose" button. You will have the choice to either import, export, or synchronize in the Operation area.