A door knob is a round or oval handle used to open and close doors. Typically made of materials like metal, plastic, or glass, door knobs are designed to be grasped and turned. They often come with a locking mechanism for added security, allowing users to secure a room or space. Door knobs are available in various styles and finishes, making them a popular choice for both functional and decorative purposes. They can be found in homes, offices, and public buildings, serving as an essential component of doors and contributing to the overall design of a room.