A box spring is a type of bed base designed to support a mattress. It typically consists of a wooden frame covered in fabric, with springs inside that provide additional support and shock absorption. Box springs help to extend the life of a mattress by absorbing impact and distributing weight evenly. Box springs are often used in conjunction with mattresses to create a complete sleeping system. They come in various sizes to match different mattress dimensions, such as twin, full, queen, and king. Many people choose box springs for their ability to elevate the mattress, making it easier to get in and out of bed.