The hinge side refers to the side of a leaf on which the fixing hinges or bands are attached. It is the constructive counterpart to the closing and handle side. Correctly specifying the hinge side is essential for ordering and installing windows and doors, as it defines the direction of the stop. According to DIN EN 12519 and common industry conventions, the hinge side is described as left or right when viewed from inside. The hinges must permanently bear the weight of the leaf and ensure ease of operation. Concealed hinges improve burglar resistance and aesthetics, while surface-mounted hinges allow easier installation.