According to wikipedia, Service-oriented architecture (SOA) is a method for systems development and integration where functionality is grouped around business processes and packaged as interoperable services. SOA also describes IT infrastructure which allows different applications to exchange data with one another as they participate in business processes.
Here is a humorous approach to understanding SOA through the eyes of "Greg the SOA Architect", systems architect. http://www.youtube.com/watch?v=5bKAG7G1rzg
There is an entire series of these videos that will enlighten you on the concept of Service Oriented Architecture.
Lighten up and Laugh!
