An innerspring mattress is a type of mattress that uses a core of metal coils or springs to provide support. These coils are typically made from steel and are designed to respond to body weight, offering a balance of comfort and firmness. The mattress is often layered with padding materials like foam or fiber for added comfort. Innerspring mattresses come in various designs, including continuous coils and pocketed coils, which affect their feel and support. They are popular for their durability and breathability, making them a common choice for many sleepers.