The document discusses service-oriented architecture (SOA) and its evolution. It describes SOA as being organized into layers for increased flexibility, reuse, standardization at lower levels, customization at higher levels, separation of concerns, and varying policies by layer. The major service types discussed are basic services, which are data-centric, logic-centric, and stateless with high reusability, and composed services, which expose harmonized access to basic services and encapsulate business workflows.