Basically, relationship of the interior and exterior spaces of architecture, also, the relationship is always an indication of the architecture type. Corbusier believed that all historical background of the architecture just focus on osmium of the wall. Size of the opened space is an indication of its correlation with the adjacent environment; namely, entrance is a combination of differently structured spaces rather than just an opening and “Porch” is one of the mentioned elements of the Iranian architecture. It is multifunctional; the porch separates the entrance from the corridor and the courtyard; it is an independent space including stone benches for seating and social interactions. This paper is defining the porch, to know why and how the independent element is developed in Iranian residential architecture. The porch is analyzed for its function and form; some concepts are discussed in the process of porch development including: privacy, climate, joint and so forth.