A door sweep is a narrow strip that attaches to the bottom of an exterior door. It is designed to seal gaps between the bottom of the door and the threshold, preventing air, water, pests, and other elements from entering the house. Door sweeps come in different shapes and materials, including solid strips of rubber or plastic, fine brush-like bristles, and soft foam. They can be installed on the outside face of exterior doors to prevent snow, dirt, and pests from collecting underneath the door. Door sweeps can be slid beneath the door or surface-mounted to the bottom of the door. Automatic door bottoms are another type of door sweep that provides a better seal than traditional door sweeps. They are adjustable and bulkier than traditional door sweeps, but they can be more effective in sealing the gap at the bottom of the door. Installing a door sweep is a simple and inexpensive way to lower heating and cooling bills and protect the door from water intrusion.