A door sill is the horizontal piece of material located at the bottom of a door frame. It serves as a barrier to prevent water, dirt, and drafts from entering a building. Typically made from wood, metal, or composite materials, the door sill is an essential component for maintaining the integrity of a doorway. In addition to its protective function, the door sill also provides structural support for the door itself. It helps to keep the door aligned and can enhance the overall aesthetic of the entrance. Proper installation and maintenance of the door sill are important for ensuring longevity and functionality.