Service Oriented Architecture or SOA is an application architecture, in which application components or "services" are defined using common interfaces utilizing a set of common protocols and tools to define how services will be invoked, and interact in a loosely coupled manner

• SOA is evolution from component based architecture, object oriented model and distributed systems (DCOM, CORBA, J2EE etc)
• SOA is not ESB but ESB is a component to enable SOA
• SOA is not a Web Service, but SOA enables Web Services
• SOA is the next evolutionary step in computing world
• SOA is yet to have a standard reference model
• SOA is still progressing towards maturity