  The properties of money commonly referenced in the economics literature were
originally identified by Jevons (1876) and Menger (1892) in the late 1800s and
were intended to describe physical currencies, such as commodity money,
metallic coins, and paper bills. In the digital era, many non-physical
currencies have either entered circulation or are under development, including
demand deposits, cryptocurrencies, stablecoins, central bank digital currencies
(CBDCs), in-game currencies, and quantum money. These forms of money have novel
properties that have not been studied extensively within the economics
literature, but may be important determinants of the monetary equilibrium that
emerges in the forthcoming era of heightened currency competition. This paper
makes the first exhaustive attempt to identify and define the properties of all
physical and digital forms of money. It reviews both the economics and computer
science literatures and categorizes properties within an expanded version of
the original functions-and-properties framework of money that includes societal
and regulatory objectives.
