With our collaborator Prof. Noo Li Jeon at Seoul National University, we prepared an educational review paper on engineering organ-on-a-chip to accelerate translational research.  We provide an overview of what is organ-on-chip, where it can be used, what it is composed of, how it can be fabricated, and how it can be operated. We also revisited the recent applications, where different organs are modeled on the microscale using this technology.