I

incremental change synchronization (ICS)

A mechanism to monitor, export, and import changed items (both hierarchy and content) between a database and an information store or between two information stores. ICS is used within Microsoft Exchange Server for local replication and for backup of information store data. The collector and synchronizer that ship with Microsoft Exchange Server can be used to provide customized incremental change synchronization, using an external agent.

information store

The default message store provider for Microsoft Exchange Server. The information store consists of three implementations of MAPI message stores: the public information store, the private information store, and the personal folder store (PST). The information store organization of public folders, private folders, and messages is referred to as the organization hierarchy. Another implementation of a MAPI message store is configured when a user works offline. It is called the offline folder store (OST) and mirrors the structure of the mailbox while offline.