In this module, we start our journey down the Stack to explain the world of informatics and health IT. We explore the top four levels of the Stack (World, Organization, Roles, and Functions), and then proceed to discuss new US medical-care (“World”) policies that drive health care Organizations to change practice, so they can accomplish their core Functions. We also discuss the history of health IT in relation to such policies in the past. We begin a course-long discussion of interoperability (which occurs at each level of the Stack), and privacy/confidentiality/security. We end with an explication of methods used to Evaluate whether an IT project has achieved the Organizational goals set for that project.