Since the turn of the millennium, competency-based medical education (CBME) has become a new standard for medical training in many countries. CBME has been operationalized in detailed frameworks of competencies that every physician should demonstrate at graduation, and similar frameworks have been created for specialties. However, the competencies, describing qualities that physicians should possess, do not directly translate into everyday activities of physicians. For that reason, the Entrustable Professional Activities (EPAs) were introduced. EPAs are units of professional practice that may be entrusted to undergraduate students, once they show the competencies needed to perform them without supervision. EPAs have become a popular topic within CBME programs in many countries and hundreds of publications within only a few years. This paper was written to introduce the strengths and weaknesses of EPAs. After a brief historical overview, the reason why EPAs are a bridge between a competency framework and daily clinical practice is explained. While competencies are qualities of individuals, EPAs are units of work. The two can be seen as two dimensions of a matrix, showing that almost all activities in health care are based on multiple competencies, such as communication skill, collaboration, professional behavior, content knowledge. Next, entrustment decision-making as a form of assessment is created and a framework of levels of supervision is presented. Entrustment decisions focus on the level of supervision a student requires for a specific activity, divided into five levels (1: allowed to observe; 2; allowed to perform under direct supervision; 3: allowed to perform under indirect supervision; 4: allowed to perform the activity unsupervised; 5: allowed to supervise the activity performed by more junior learners). For readers interested in applying the concept to practice, a stepwise approach to the curriculum development is proposed. The paper concludes with an overview of the state-of-the-art of working with EPAs across disciplines, professions and countries.