The document provides an overview of multi-domain orchestration and network service orchestration (NSO), detailing the definitions, functions, and challenges in implementing orchestrators across various administrative domains. It emphasizes the need for automated resource management, the integration of network function virtualization (NFV) and software-defined networking (SDN), as well as acknowledging the hurdles such as scalability, interoperability, and security. Additionally, it discusses the significance of orchestration for applications in 5G, the Internet of Things (IoT), and intelligent transport systems.