What is "box-spring"

n. Any of a set of spiral springs set into a box spring.

A box-spring (or divan in the UK) 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 castors. The box-spring is usually the same size as the much softer mattress that is placed on it. Working together, the box-spring and mattress (with 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.

The purpose of the box-spring is threefold:

• to raise the mattress' height, making it easier to get in and out of bed;
• to absorb shock and reduce wear to the mattress; and
• to create a flat and firm structure for the mattress to lie upon.

The first rectangular spring-cushioned wire frames to support mattresses did not have wood rims or cloth covers. These were called bedsprings. More and more box-springs are being made out of wood, then covered in fabrics. Wood makes a better support system for the newer memory foam and latex mattresses. The newest design in box-springs is the folding box spring made of wood or metal, then covered in fabric which can fold in half and can be sent by shipping and courier companies.

With the increasing height of mattresses, manufacturers now make box springs in different heights. Standard "high profile" box springs are in height, whereas "low profile" box springs are between . The difference between the two heights is purely aesthetic and makes no difference in the support provided for the mattress.