The aim of the article is to systematize fundamental concepts involved in the philosophical debate on realism and idealism. In the first (historical) part distinction between appearance and reality (which has its roots in ancient philosophy) is presented as one of the sources of the modern debate on realism and idealism. In this part different interpretations of realism and idealism (Descartes, Leibniz, Berkeley, Kant, Heidegger, Moore, Carnap) are also analyzed. The second part is concerned with definitions of four fundamental oppositions: metaphysical idealism and epistemological idealism, metaphysical realism and epistemological realism. The third part discusses different forms of realism (naive realism, critical realism, scientific realism, transcendental realism and conceptual realism) and introduces the concept of antirealism. Fourth part deals with connections between realism and idealism debate and such philosophical standpoints as skepticism, agnosticism and solipsism.