A backrest is the part of a chair, couch, or seat that supports your back while you sit. When you settle into a comfortable chair after a long day, that upright part behind you that lets you lean back and relax is the backrest.

Backrests come in all shapes and sizes. An office chair usually has a tall, curved backrest that follows the shape of your spine. A wooden dining chair might have a simple straight backrest with vertical slats. Some camping chairs have fabric backrests that angle backward for lounging.

The design of a backrest matters more than you might think. A good backrest helps you sit comfortably for hours while reading or doing homework. A poorly designed one can make your back tired and sore. That's why ergonomic chairs (chairs designed for comfort and health) have carefully shaped backrests that support the natural curve of your spine. Even car seats have backrests that can tilt and adjust so drivers and passengers stay comfortable on long trips.