SOA is an architectural style that primarily promotes service orientation.

Service orientation implies loosely-coupled systems that are fundamentally focused on satisfying the business functions. In SOA, you think in terms of services that fulfill business processes in a self-contained manner.

It is easier to look at SOA as the solution to interfaces and integration problems, but it provides much more. SOA is more than just an integration framework. It defines the vision and approach to enterprise architecture that builds upon software services representing heterogeneous business functions. SOA promotes an overall approach by scoping the main business landscape, identifying the business units and relevant stakeholders, then defining or improving the business processes, and exposing the interfaces and solutions in terms of reusable, self-contained, interoperable, flexible software services.

SOA also mandates setting up operational cycles for running healthy systems as well as for maintenance and upgrade cycles. It not only enables the registry and discovery framework for services, but also provides the platform for the governance of software services that ultimately monitors, reports, and governs the business functions for the relevant business units in an enterprise.