In vivo NMR is a non-invasive, powerful technique used for the study of biological reactions and processes inside isolated cells, tissues and organs in animal models and humans. This text covers the principles of in vivo NMR techniques as well as practical and experimental considerations. Using vector diagrams and 2D images, it explains NMR theory in a graphical manner and also discusses NMR experimental techniques with relevance to practical considerations, allowing users to choose an appropriate method for application.