A door hanger is a marketing or informational tool that is typically made of paper or cardstock and designed to hang from a door knob or handle. It is used for various purposes, such as advertising products or services, conveying important messages, or promoting events. Door hangers are often used by businesses, political campaigns, hotels, and organizations to directly reach residents or customers at their homes or hotel rooms. They are known for their effectiveness in grabbing attention since they are placed prominently on a door and are likely to be noticed when the door is opened.