A king size mattress is a large bed designed to provide ample sleeping space for couples or individuals who enjoy extra room. It typically measures 76 inches wide by 80 inches long, making it one of the largest standard mattress sizes available. This size is ideal for those who share a bed, as it allows for comfortable movement without disturbing a partner. King size mattresses come in various types, including memory foam, innerspring, and latex, catering to different sleep preferences. They are often paired with a matching king size bed frame to support the mattress and enhance the overall bedroom aesthetic.