Book excerpt: Precision medicine is rapidly becoming the standard-of-care for the treatment of cancer patients. This is made possible, in part, by the ready availability and reasonable costs of comprehensive DNA and RNA sequencing assays. However, precision medicine is complex and incorporates entirely new types of data and treatment paradigms that are outside of the training of most oncologists in practice today. Precision Medicine Oncology: A Primer is a concise review of the fundamental principles and applications of precision medicine, intended for clinicians, particularly those working in oncology. It provides an accessible introduction to the technological advances in DNA and RNA sequencing, gives a detailed overview of approaches to the interpretation of molecular test results and their point-of-care implementation for individual patients, and describes innovative clinical trial designs in oncology as well as characteristics of the computational infrastructures through which massive quantities of data are collected, stored, and used in precision medicine oncology.