A cluster is a group of loosely-connected computers that work together in such a way that they can be viewed as a single system. The components (or nodes) of a cluster are usually connected to each other through fast local area networks, each node running its own operating system. Clustering middleware orchestrates collaboration between the nodes, allowing users and applications to treat the cluster as a single processor. Clusters are effective for scalable enterprise applications, since performance is improved by adding more nodes as required. Furthermore, if at anytime one node fails, others can take on its load.