# What is a Casement Window?
**A casement window is a window type that is attached to its frame with hinges along one vertical edge and swings open like a door, either inward or outward.** It is one of the oldest and most common window types in western building tradition.
## Features
– **Side-hinged** — the window pivots on a vertical axis
– **Fully openable** — unlike a sliding sash window, a casement can be opened completely
– **Excellent ventilation** — the wide opening angle provides optimal airflow
– **Good weather seal** — when closed, the window presses against the rebate for a tight fit
## Variants
– **Single casement** — one opening sash within the frame
– **Double casement** — two sashes opening to either side with a central mullion
– **Outward opening** — standard in British and American tradition
– **Inward opening** — common in continental European tradition
– **Tilt-and-turn** — a modern variant that can both swing and tilt
## Application
Casement windows are used in residential buildings, historic properties, listed buildings and modern architecture with aluminium or uPVC profiles.
## Related Terms
– Window
– Window frame
– Hinged window
– Rebate
– Glazing
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