backrest

Backrest refers to the portion of a seat that supports the sitter's back. It is typically attached to the seat frame and extends upward behind the user to provide support and guidance for spinal alignment. Backrests vary in height, contour, and angle. Some are flat, others are curved or contoured to follow the natural S-shaped curve of the spine, and many include an adjustable recline or tilt mechanism to accommodate different postures and activities.

Materials range from solid wood or metal frames to foam-padded upholstery covered in fabric, leather, or synthetic materials. The design often incorporates lumbar support, either built into molded foam or via adjustable inserts, and may include integrated headrests or shoulder support in higher-end chairs. In seating intended for long-term use, ergonomics emphasize adjustable backrest height, tilt tension, and lumbar support to reduce pressure and promote proper posture.

In cars and aircraft, backrests are part of the seat unit and are frequently adjustable; headrests are often integrated to reduce whiplash and improve comfort. In wheelchairs, backrests provide support for varying trunk stability and may be contoured or modular to accommodate users with limited mobility.

Environmental and durability considerations include breathable upholstery, ease of cleaning, and resistance to wear. The backrest is a fundamental element of seat design with significant impact on comfort, posture, and fatigue during sitting.