The dynamics of the business and of the information systems that support it are quite different. Business is driven: internally by the enterprise mission and its strategy and externally by the nature of the markets and by statutory obligations
Information systems are driven internally by the automation strategy (if any) and externally by technology trends and available vendors.
Service-Oriented Architecture is an approach to addressing this challenge: while the IT resources of an Enterprise must be aligned to serve the needs of the business, they must also be free to evolve in the best and most efficient way possible.
The concept of service serves as the common link between the two dynamics.
Synonyms:
SOA, Service Oriented Architecture