Networks and deposits
Memo / Destination tag
Data attached to a transaction identifying the final recipient behind a shared address.
On XRP Ledger, Stellar and TON, opening an account requires locking a reserve in the native asset. Services therefore use one address for all customers and distinguish them by a label attached to each transaction: Destination Tag, Memo, or comment depending on the network.
Without that label the transaction does land on the account but nothing says whose it is. The deposit then goes into manual reconciliation, and returning it requires proof of control of the sending address. If the recipient is another service, recovery depends entirely on its policy — the leading source of permanent losses on these networks.