So it's a ledger system using an atomic units rather than symbolic ones? Worried about my word choice here
![Undecided](https://bitcointalk.org/Smileys/default/undecided.gif)
Kind of, but the atomic units are not atomic units of accounts (like satoshis = 0.00000001 BTC), but atomic outputs whose amounts vary.
If you send 1.5 BTC to a given address X, this address will have one "input" of 1.5 BTC that can later be spent. Later, if the owner of address X wants to send 1 BTC to another address Y, he must destroy entirely the 1.5 input, and create two new outputs: 1 BTC to Y, and 0.5 BTC back to himself.
It's similar to cash actually: to pay 4.5$ you either group several coin of different value to reach 4.5, or you pay with 5$ and the merchant give you 0.5$ back. Except with bitcoin (and monero, and all others) it is not coin and notes but outputs between addresses, and the values of them is not always the same as with coins.