A pithy explanation of Austrian Business Cycle Theory, from Chris Lingle at TechCentralStation:
This fractional reserve banking system allows banks to engage in credit creation by issuing notes and bank balances unsupported by any new wealth. Since money substitutes are created out of thin air, the whole process is a risky venture. On its face, such a practice would be fraudulent except that it has a legal basis whereby central banks give commercial banks the legal right to issue “counterfeit” money.