Memo
An extra field on some blockchains that identifies who a payment is for when many users share one address.
A memo is a short piece of data attached to a transaction. On networks such as Stellar (XLM), Hedera (HBAR), TON and some others, exchanges often use one shared deposit address for all customers and rely on the memo to tell deposits apart. Depending on the chain, the field may be called memo, comment or message.
If a service shows a memo together with the deposit address, you must enter it exactly. Without it, the payment arrives at the shared address but cannot be matched to your account or order automatically. Recovery is usually possible through support, but it takes time and sometimes a fee.
Personal wallets do not need a memo, because each user has their own address. On the XRP Ledger the same role is played by the destination tag, which is a number rather than free text.
