Complex sentence: Service-oriented architecture (SOA) is a software design and software architecture design pattern based on structured collections of discrete software modules, known as services, that collectively provide the complete functionality of a large software application.
Split into simpler sentences: Service-oriented architecture (SOA) is a software design and software architecture design pattern based on discrete pieces of software that provide application functionality as services, known as Service-orientation. Services can be combined by other software applications that together, provide the complete functionality of a large software application.