Exchange ActiveSync is used by VersaMail to synchronize Email and Calendar between your Treo smartphone and the Exchange server.

Microsoft describes its product: "Exchange ActiveSync is a server-side technology that allows mobile devices to synchronize inbox, calendar, and contacts remotely with Exchange rather than using a desktop PC, cradle, and desktop synchronization software."

Remember, although Exchange ActiveSync technology is capable of synchronizing Contacts, the Treo smartphone version of VersaMail does not include this feature. On your Treo smartphone, Exchange ActiveSync applies to Email and Calendar synchronization.

When you use Exchange ActiveSync to synchronize Email and Calendar on your Treo smartphone, the information on your smartphone is compared with the information on the Exchange server for your account. If there are any differences (e.g. if you were on the road and added a Calendar appointment to your smartphone), they are resolved during the Exchange ActiveSync operation (e.g. the appointment is added to the Exchange server). Since the Exchange Server drives Outlook, when you get back to your desk, you'll see the new appointment in Outlook as well.

Microsoft Exchange Server

In Microsoft's words, this is the "messaging and collaboration software that runs on servers that enables you to send and receive electronic mail and other forms of interactive communication through computer networks."

When you use Outlook, your Email, Calendar, Contacts and other information comes from the Exchange Server. Likewise, when you synchronize Email and Calendar using Exchange ActiveSync on your Treo smartphone, your device gets its information from the Exchange Server.

Usually, Exchange Server administration is handled by your organization's IT group. To the end user, the Exchange Server is an invisible backend component that drives Outlook.

Microsoft ActiveSync

This is the synchronization software package for Windows Mobile-based Pocket PCs and Smartphones. It's analogous to HotSync Manager in the Palm OS world.

Microsoft ActiveSync as a whole is not used in Palm OS products, but the Exchange component of ActiveSync (i.e. Microsoft Exchange ActiveSync) is used in both Palm OS-based Treo smartphones and Windows Mobile-based Pocket PCs to communicate with the Exchange server.