Book excerpt: This comprehensive overview of 61850 standard/protocol focuses on implementation, taking the reader through the development and concepts of IEC 61850. This includes the initial work by General Motors (Manufacturing Automation Protocol), EPRI (UCA 1.0 and UCA 2.0), IEEE (TR 1550), and IEC 61850. The standard is a significant piece of many IIoT (industrial internet of things) strategies for substation communication. The book discusses and documents the basic research and theory of guaranteed multicast done for IEC 61850 GOOSE as well as the shift from variable technology to object oriented technology. The layering principles, as well as the structure, of IEC 61850 are discussed in detail as well as the actual communication profiles that have been created to support substation/distribution automation, distributed energy resources, and synchrophasors. Real applications will be discussed as well as the future direction of the standard. The author is a technical co-editor of IEC 61850 standard and a leader in US implementations, having been involved with the technology from its inception.