The most important of these terms is probably the word “service” itself, which the glossary defines as a product that is intangible and non-storable. While this definition accurately captures the intended scope of meaning for the word “service,” it does not highlight some of the possible subtleties or misunderstandings of this concept in the CMMI context.

The first point to highlight is that a service is a kind of product, given this definition. Many people routinely think of products and services as two mutually exclusive categories. In CMMI models, however, products and services are not disjoint categories: a service is considered to be a special variety of product. Any reference to products can be assumed to refer to services as well. If you find a need to refer to a category of products that are not services in a CMMI context, you may find it helpful to use the term “goods,” as in the commonly used and understood phrase “goods and services.” (For historical reasons, portions of CMMI models still use the phrase “products and services” on occasion. However, this use is always intended to explicitly remind the reader that services are included in the discussion.)

A second possible point of confusion is between services and processes, especially because both terms refer to entities that are by nature intangible and non-storable, and because both concepts are intrinsically linked. However, in CMMI models, processes are activities, while services are a useful result of performing those activities. For example, an organization that provides training services performs training processes (activities) that are intended to leave the recipients of the training in a more knowledgeable state. This useful state of affairs (i.e., being more knowledgeable) is the service that the training provider delivers or attempts to deliver. If the training processes are performed but the recipients fail to become more knowledgeable (perhaps because the training is poorly designed, or the recipients don’t have some necessary preliminary knowledge), then the service—the useful result—has not actually been delivered. Services are the results of processes (performed as part of a collection of resources), not the processes themselves.

A final possible point of confusion over the meaning of the word “service” will be apparent to those who have a background in information technology, especially those who are familiar with disciplines like service-oriented architecture (SOA) or software as a service (SaaS). In a software context, services are typically thought of as methods, components, or building blocks of a larger automated system, rather than as the results produced by that system. In CMMI models, services are useful intangible and non-storable results delivered through the operation of a service system, which may or may not have any automated components. To completely resolve this possible confusion, an understanding of the service system concept is necessary.