[hgomersall]

Nit picking, but what "makes it money" is the fact you can redeem it; that is, some entity views your money as a liability.

It's totally fungible though.

[cdchn]

From Wikipedia via the IMF money is: Fungible: its individual units must be capable of mutual substitution (i.e., interchangeability). Durable: able to withstand repeated use. Divisible: divisible to small units. Portable: easily carried and transported. Acceptable: most people must accept the money as payment Scarce: its supply in circulation must be limited.[27]