A casement window is a type of window that is hinged on one side and opens outward, similar to a door. This design allows for maximum ventilation, as the entire window can be opened to let in fresh air. Casement windows are often operated with a crank mechanism, making them easy to open and close. These windows are commonly made of wood, vinyl, or aluminum, and they can be found in various styles to match different architectural designs. Casement windows are known for their energy efficiency, as they create a tight seal when closed, helping to reduce heating and cooling costs.