You often hear people say that Bitcoin is a pseudonymous system, and that it's not anonymous. What is the actual difference in the context of electronic money?
Pseudonymity means that you can see the payment history of a pseudonym (eg an address), but there's no way (in the system itself) to link the pseudonym to a person.
What would an anonymous system look like? I am aware of Chaumian e-cash (https://bitcoin.stackexchange.com/a/10666/69518), but what properties must anonymous electronic cash have? Is it what Andrew Poelstra alludes to:
Total anonymity, in the sense that when you spend money there is no trace of where it came from or where it's going, is theoretically possible by using the cryptographic technique of zero-knowledge proofs.
So you can see a payment, but you can't see where the money is coming from or where it's going (just like chaumian e-cash). Would anything less than this be considered not anonymous? I'm not looking for solutions, only what properties are needed for an electronic money system to be anonymous.