An IT service catalog, sometimes called an IT service portfolio, is a list of available technology resources and offerings within an organization.
An IT service catalog contains information about deliverables, prices, contact points and processes for requesting a service. Typically a catalog will have two views, a customer-facing view from which business users can browse and select services -- and a technical view that documents exactly what is required to deliver each service in the catalog.
IT service catalogs were introduced in ITIL v3 as a best practice for service management. ITIL defines an IT service catalog as a "database or structured document." Experts recommend that if an IT organization is interested in developing an IT service catalog, they begin by taking inventory of all the services they offer. Once the catalog has been created, someone in the IT department needs to manage the implementation, promotion and lifecycle of the catalog. When possible, it can be helpful to have workflow software automate service delivery.
Eric Feldman (from CA Technologies) explains why an IT service catalog is also a useful tool for communicating the value an IT department brings to a business.