Dutch door

A Dutch door (American English), or stable door (British English), or half door (Hiberno English), is a door divided horizontally in such a fashion that the bottom half may remain shut while the top half opens. Known in early New England as a double-hung door. The initial purpose of this door was to keep animals out of farmhouses, or keep children inside, while allowing light and air to filter through the open top. And when the top half was open they also allowed the breeze, but stopped the wind from blowing street and lawn dirt into the house. This type of door was common in the Netherlands in the seventeenth century and appears in Dutch paintings of the period. They were also commonly found in the Dutch cultural areas of New York and New Jersey before the American Revolution.