A twin size mattress measures 38 inches wide by 75 inches long, making it a popular choice for children, teenagers, and small guest rooms. Its compact size allows it to fit easily in tight spaces, such as dorm rooms or studio apartments. These mattresses are available in various materials, including memory foam, innerspring, and latex, catering to different comfort preferences. Twin size mattresses are often paired with twin size bed frames and bedding, making them a versatile option for many sleeping arrangements.