"An SOA is a collection of these services communicating with each other, either through simple passage of data or a coordinated effort to do a task. To get them to communicate, you need Web services. We used to buy a stereo system as a single integrated unit, all hardwired together--the speakers, the receiver, the tuner, and the turntable. Some stereos had a better receiver, while some had a better turntable. One day somebody figured, 'Hey, wouldn't it be great if we could mix and match components?' Now the bits and pieces work together, connected by standardized wiring."