Catalogs are another way of provisioning a set of instances or virtual machines and are used to create application stacks that contain more than one instance or virtual machine. For example, let's consider a multi-tier web application that contains a web tier, an application tier and a database tier, and we want our stack to consist of two instances in each tier for high availability and failover. Instead of provisioning each instance manually, we can create a catalog that contains the entire deployment information, thus referred to a single template to provision the entire stack. When provisioning is enabled in a catalog, it is called a service catalog.

Catalog Items, Catalogs, and Service Catalogs are accessible from the Catalogs tab in the Services menu.