box-spring

thumb|Box-spring thumb|Queen size box-spring on metal bed frame thumb|8-way hand-tied box spring

A box-spring (or divan in some countries) is a type of bed base typically consisting of a sturdy wooden frame covered in cloth and containing springs. Usually, the box-spring is placed on top of a wooden or metal bedframe that sits on the floor and acts as a brace, except in the UK where the divan is more often fitted with small casters. The box-spring is usually the same size as the much softer mattress placed on it. Working together, the box-spring and mattress (with an optional bed frame) make up a bed. It is common to find a box-spring and mattress being used together without the support of a frame underneath, the box spring being mounted directly on casters standing on the floor.