This entry begins by presenting the origin, history and etymology of the term, as well as a short definition of epistemology as the discipline that deals with the nature, origin, validity and limits of knowledge. Then we focus on the classical platonic analysis of knowledge as truth justified belief. Against the backdrop of this platonic notion we present other relevant perspectives. It is essential to follow the history of the relation between origin and justification of knowledge until the contemporary separation of both problems. The study of the origin of knowledge seems to require a naturalized epistemology, while the problem of justification is usually approached from a philosophical point of view, whether coherentist, foundationalist or fallibilist. However, currently some authors are advocating for a full naturalized epistemology, while others are extending the philosophical point of view also to the genesis of knowledge.