Mattresses typically have 3 layers: The foundation, the mattress core and the upholstery.

The Foundation: As the name implies, this layer is the base of the mattress. The foundation is either box springs, wooden, or a mix of wood and steel. Box-springs consist of a rigid frame which contain extra-heavy-duty springs. This type of foundation contributes to softer support and a bouncier mattress.

The Mattress Core: The mattress core is the most important part of the mattress and is usually made up of steel coils. The four types of coils commonly used are bonell coils, marshal coils, offset coils and continuous coils. It is widely believed that more the number of springs, more comfortable the mattress.

The Upholstery: Upholstery layers cover the mattress and provide cushioning and comfort. The upholstery layer consists of three parts: the insulator, the middle upholstery, and the quilt.