Doors are structures that serve as a barrier or gateway between spaces, offering both security and accessibility. They come in various materials such as wood, metal, or glass, and can be designed for different functions, including interior and exterior use. Doors can be simple or ornate, featuring elements like handles, locks, and hinges, and may open in different ways, such as swinging, sliding, or folding. They are essential for privacy, protection, and the aesthetic enhancement of any building or room.