The major and primary purpose is to provide security. They provide access into and out of a space. They control access to the doorway. Provide protection against potential threats such as burglars, intruders, and even natural disasters. Many doors are equipped with locks. Ensures privacy by preventing unwanted attention from outsiders.Allows the inflow of positive energy for the well-being of its occupants. Control the ventilation or air drafts so that interiors may be more effectively heated or cooled Dampening the noise. Separating areas with different functions. Draws attention and add character to interior and exterior spaces Should attract the attention of neighbors, but deter the attention of burglars Should give good impression for visitors and the passersby. At the same time the practical purposes and functionality like security, insulation, and durability will determine the particular door design.