In recent years, semantic and physical aspects are highly discussed, since the majority of experts believe ignoring these dimensions have resulted in reduced quality of living spaces. The concept of "threshold" is among these concepts, whose semantic aspects are frequently forgotten due to prevalence of the simplistic views. The "Threshold", as a concept or as an aspect, can cover a wide range of meanings associated with the meaning of space. This aspect can affect the presence and appearance of the space and it can bring quality to the space. Therefore, the current paper aims at recognizing the different physical and semantic aspects of "threshold" in Persian gardens by studying its features and characteristics. The research method in this paper is descriptive-analytical and the data is gathered through library and documentary research. At the first glance, a threshold is considered as an identifiable concept that can be defined based on its physical elements and semantic layers. It can also be identified objectively and subjectively according to its function. In addition, this specific type of space has a different design and form that can offer different spatial qualities in different types of gardens and thus presenting features of the inside and outside.
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