New technologies that make currencymaking more convenient, safer and cheaper will lead to new forms of money that people are more willing to use. With the advancement of technology such as computers, the Internet, and cryptography, many new forms of currency such as digital currency, virtual currency, and cryptocurrency have emerged. However, the definition of related concepts is very vague, which cause some confusions. This paper combines logical relations and historical development, by starting with physical money and money of account, to sort out the evolution of monetary forms, to focus on the emerging cryptocurrency, to make a clear conceptual definition of these monetary forms, and to have clarified their relationship.