The document discusses the evolution of money and its classification. It begins by outlining some difficulties with barter systems, including the lack of a common measure of value and difficulty making deferred payments. It then describes the stages in the evolution of money, starting with commodities and progressing to metallic money, paper money, and credit money. The document further classifies money based on monetary system criteria such as legal tender status, and distinguishes between money of account and actual money used to settle debts.