Information science is an interdisciplinary field that shares some common foundations with health informatics. Both disciplines are focused on information and its use, how it is created and managed, and the technical and social issues impacting its access and use. In health informatics, of course, interest in the interactions across information, technology, and people is almost exclusively within healthcare contexts across the biomedical community. However, many of the methods, knowledge, and tools from information science can and have informed health informatics over the years. In this chapter, we explore some of the basics of information science relevant to the study and practice of health informatics. We begin by looking at definitions relevant to the field. Then, we briefly review the importance of information retrieval, including principles and tools related to the organization of information. Lastly, given that information science has a major focus on users, we overview information behaviors and use.