This chapter from Outdoor Emergency Care: A Patroller's Guide to Medical Care (6th edition) outlines the essential components and principles of Outdoor Emergency Care (OEC) for technicians and ski patrollers. It details the resources available for both instructors and students, including textbooks, online modules, and skill guides, to facilitate learning. The core objectives emphasize understanding attributes of emergency care systems, different prehospital provider levels, types of medical oversight, and the purpose of quality improvement. Crucially, it highlights the history and evolution of emergency care systems, emphasizing the coordinated, organized, and continuously improving nature of patient care from initial contact to definitive treatment, particularly in outdoor, non-urban settings where OEC technicians often operate. The text also elaborates on the 14 attributes of effective EMS as outlined by NHTSA, such as integration of health services, medical direction, communication, and public access, alongside different levels of emergency personnel and the vital role of medical oversight and protocols in ensuring consistent, high-quality care.