It's the total amount of money passing trough the network.
But since bitcoin transactions work by sending "change" back to yourself this value is not that relevant. In most cases 90% of the transaction amount is sent back as change.
But since bitcoin transactions work by sending "change" back to yourself this value is not that relevant. In most cases 90% of the transaction amount is sent back as change.
If the ratio of 'money spent'/'total volume' is 1/5, does that mean that people are, on average, spending one fifth of their wallet?
Bitcoin wallets generally contain multiple addresses, and transactions will be created with inputs associated with only a subset of these addresses.
This means that the Bitcoins in somebodies wallet is conceptually the list of transactions that have been made to them (that haven't been spent yet). It also means that a nice big graph can be made of how money is (or isn't) flowing through the system.