Definition & Meaning of "box spring"

What is a "box spring"?

A box spring is a rectangular support structure placed under a mattress to provide extra stability and height to the bed. It is typically made of a wooden or metal frame and is filled with coils or a sturdy material to absorb weight and prevent the mattress from sagging. Box springs help extend the life of the mattress and make the bed more comfortable to sleep on. They come in different sizes to match various mattress dimensions and are usually used in combination with a bed frame.