by Jacob Goldstein
$100 bill
Doug Mills/AP

What is money?
...money itself is completing a developmental arc from matter to bits, stored in computer memory and magnetic strips, world finance coursing through the global nervous system. Even when money seemed to be material treasure, heavy in pockets and ships' holds and bank vaults, it always was information. Coins and notes, shekels and cowries were all just short-lived technologies for tokenizing information...
This is from The Information: A History, a Theory, a Flood, a new book by James Gleick.
From the Planet Money vault, here are four more answers to the same question:
1. Money is fiction.
From The Invention of Money
2. Money is a giant stone at the bottom of the sea.
From The Island of Stone Money
3. Money is gold.
From A Chemist Explains Why Gold Beat Out Lithium, Osmium, Einsteinium ...
4. Money is trust.
From A Wingnut Argument For The Gold Standard