Footballs are spherical balls used in the sport of football, also known as soccer in some countries. They are typically made of leather or synthetic materials and are designed to be lightweight and durable. The standard size for adult footballs is Size 5, which has a circumference of about 68-70 centimeters. In addition to traditional football, the term "football" can refer to various other sports, such as American football and Australian rules football. Each type of football has its own specific ball design and size, tailored to the rules and gameplay of that sport.