This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book introduces the reader to debates regarding the terminology used in medical travel studies and the main concepts. It provides an overview of some of the critical perspectives used in health services research, emphasizing the critical (im)mobilities framework. The book presents an ethnographic case study of intra-national medical travel by discussing the findings from research on the experiences of families seeking pediatric oncology treatment in Argentina. It focuses on medical travel infrastructure, that is, the processes, structures, and practices that make medical travel possible for some, but not for others. The book demonstrates the importance of studying the everydayness of health-seeking practices. It proposes the development of a medical travel research agenda based on the critical perspectives.