By using Oracle WebLogic Server clusters you can create a network of clustered application servers to provide highly available and scalable applications that are capable of providing service in the event of a machine or hardware component failure.
WebLogic Server clusters are a network of WebLogic Server instances that work together as a server farm to provide a highly available web service. Each instance is a fully functioning application server. You can deploy several applications to the entire cluster, thus making the cluster function as a single unit providing the same application across all machines in the cluster.
Web clients connect to the cluster through either a cluster-aware proxy application (an application provided by WebLogic Server that includes built-in load balancing) or a vendor load balancer. In either case, the web client connects to one address and is transparently redirected to a machine within the cluster.