Improvisation has a particularly important position in the practice and tradition of Iranian classical music. In Iran, it is one of the critical areas of improvisation, which has been rarely researched. Musicians cannot explain their improvisation process. The concept and process of Improvisation have always been vague and unknown. It has been mixed with beliefs, mysticism, and traditional attitudes. This paper is a Phenomenological study in a philosophical hermeneutic approach that has introduced some unknown aspects and hidden angles of this specific phenomenon. At first, this research studies pre-concepts, pre-understandings, and prejudices around the phenomenon, then tries to explain and determine the concept of improvisation, its features, and the way to process it. This matter has done by having a historical view of the origin of musical improvisation and finding the inherent characteristics and diversity of the phenomena and examines its similarities and differences with similar phenomena such as composition and literary improvisation. By paying attention to the etymology of the word and the best instances in the history of Iranian music, as well as the stories and anecdotes in the history of Iranian literature relating to musical and literary improvisation, the concept of freedom in improvisation has been studied. This phenomenon has been reviewed with a glimpse of Gadamer’ s “ play” concept, and the idea of Dwelling has been followed in improvisation by considering Heidegger’ s thought. Finally, improvisation has been studied as an interpretation act. Improvisation is similar to an open dialogue that the interlocutors don’ t know beforehand what will be said and heard. This dialogue is following some rules; the interlocutors are limited so that they can’ t say everything, even though they are free in expression. Musical improvisation is the concurrent creation and performance of music; and as concurrent creation and performance of poetry, compliances with the rules and principles of aesthetic tradition and practice also should be compatible with “ existing conditions” and “ prepared statuses” and appropriate to the time, place and situation where the improviser is. Requirements of becoming an Iranian musical improviser are the genius and necessary mental abilities, learning the techniques and the rules, memorizing Radifs (A repertory of Iranian music) and pieces of Iranian music, development of artistry, musical taste and musical knowledge, thinking about what is learned and analysis of what is memorized and ultimately a lot of effort, practice, endeavor, and experience. Improvisation is an interpretation of Radif, tradition, and practice of Iranian music as well as an interpretation of pre-made pieces and previous improvisations. These are interpretations that give identity to what is interpreted. Improviser dwells within the improvisation world, and it also dwells within the Radif world which, itself dwells within the world of tradition and practice of Iranian music. Dwelling inherently involves adding on, replacing, and altering. Dwelling and interpretation create responsibilities. Musical dialogue is fundamentally ethical in nature so that improvisers must be committed to this ethics.