A door sign is a sign that is attached to a door to let people know what is behind the door or who lives or works behind the door. Door signs can contain information such as the name of a person or a company, the office number or the function of a person, or the purpose of a room. Door signs can also be used to indicate whether a room is private or has limited access. They can be made of various materials such as plastic, metal, or wood, and can be made in various styles and sizes.