Since the turn of the twenty-first century, competency-based medical education (CBME) has become a dominant approach to postgraduate medical education in many countries. CBME has a history dating back half a century and is rooted in general educational approaches such as outcome-based education and mastery learning. Despite controversies around the terminology and the CBME approach, important national medical regulatory bodies in Canada, the United States, and other countries have embraced CBME. CBME can be characterized as having two distinct features: a focus on specific domains of competence, and a relative independence of time in training, making it an individualized approach that is particularly applicable in workplace training. It is not the length of training that determines a person's readiness for unsupervised practice, but the attained competence or competencies. This shift in focus makes CBME different from traditional training. In this contribution, definitions of CBME and related concepts are detailed.