What window type is commonly found in residential buildings and allows one sash to slide vertically over the other?

The double-hung window type is characterized by its two sashes that can slide vertically over one another. This design allows both the top and bottom sashes to be opened, enabling airflow from both the top and bottom of the window. The vertical sliding mechanism is not only practical for ventilation but also makes cleaning the exterior of the window more accessible from indoors, as both sashes can tilt inward.

In contrast, casement windows are hinged at the side and open outward, while horizontal sliding windows feature sashes that move side to side instead of up and down. Jalousie windows consist of overlapping glass slats that can be adjusted for ventilation, but they do not have sashes that slide vertically. The double-hung design remains the most popular choice for residential settings due to its functionality and ease of use.