The document discusses the need for enterprise service buses (ESBs) and their role in service-oriented architectures (SOAs). ESBs are needed to integrate heterogeneous information systems and ensure consistency across subsystems. They provide loose coupling between systems using standards-based integration. The document compares ESBs to other integration approaches like extract-transform-load tools, message-oriented middleware, and enterprise application integration, noting advantages of ESBs like separating mediation and orchestration roles. The key aspects of ESBs are that they provide a bus-like infrastructure to decouple applications and use adapters to transform data between application and canonical formats.