Book excerpt: Organ-on-a-Chip: Engineered Microenvironments for Safety and Efficacy Testing contains chapters from world-leading researchers in the field of organ on a chip development and applications, with perspectives from life sciences, medicine, physiology and engineering. The book contains an overview of the field, with sections covering the major organ systems and currently available technologies, platforms and methods. As readers may also be interested in creating biochips, materials and engineering best practice, these topics are also described. Users will learn about the limitations of 2D in-vitro models and the available 3D in-vitro models (what benefits they offer and some examples). Finally, the MOC section shows how the organ on a chip technology can be adapted to improve the physiology of in-vitro models. - Includes case studies of other organs on a chip that have been developed and successfully used - Provides insights into functional microphysiological organ on a chip platforms for toxicity and efficacy testing, along with opportunities for translational medicine - Presented fields (PK/PD, physiology, medicine, safety) are given a definition followed by the challenges and potential of organs on a chip