Paper money is a type of currency made from paper that is used as a medium of exchange for goods and services. It is issued by governments and central banks and typically features various denominations, such as $1, $5, $10, and so on. Paper money is designed to be durable and secure, often incorporating special features like watermarks and security threads to prevent counterfeiting. The use of paper money began in China during the Tang Dynasty (618-907 AD) and became more widespread during the Song Dynasty (960-1279 AD). Today, many countries around the world use paper money alongside coins and digital currencies, making it an essential part of the global economy.