Failover clustering is a technique used in Windows Server 2008 environment to provide high availability of applications. The cluster used in failover clustering works with shared data that can be spread across multiple systems. Failover clustering is managed through the Failover Cluster Management interface in Windows Server 2008. The Failover clustering feature is available only in Windows Server 2008 Enterprise and Datacenter editions.

In a failover clustering, there are two computers (for exmple). One provides the service in normal situations. A second computer is present in order to run the service when the primary system fails and this computer is called failover computer. The primary system is monitored to ensure that the primary system is operating correctly. As soon as the active system fails, the monitoring system detects the failure and the failover system takes over operation of the service.