TAG (Destination TAG - Memo)
Generally a Tag is a label attached to a thing for the purpose of identification.
What is a Destination TAG
During transactions of certain coins like XRP, XLM, and some others you may have noticed a TAG (Memo) is needed along with the deposit wallet address; unlike in other coins where only a wallet address is required to either withdraw or deposit.
Due to the coin management system, certain coins like XRP, XLM, and EOS use the Destination TAG technology. The purpose of it is to assign (identify) the specific recipient of the transaction.
For example you live in building 'A' and the only way to identify where exactly in the building you live is the flat or apartment number. Therefore, the building is like your wallet address and the flat or apartment number is your TAG.
Please note that most of the cryptocurrencies does not require a TAG or Memo during transactions.
For these type of coins such as XRP and XLM, you may not always be required to use a TAG for deposits and withdrawals, so therefore this field is defaulted to mandatory, but can also be check-boxed off as 'No TAG' and then not required.
Using the same example as above, this could happen when you withdraw XRP or XLM to your private wallet from the exchange and the building symbolically is your own house and there is no need for a TAG like a flat or apartment.
How to use Destination Tag (on mobile)?
Suppose you want to deposit XLM.
1. Select XLM from the wallet and then select Deposit.
2. A Disclaimer will appear reminding you that the Coin / Token you are depositing needs a TAG / Memo or the funds will be lost.
3. The next page displays the Wallet Address to deposit and the TAG (Memo).
4. Copy both the Deposit wallet address and the TAG. 
Withdrawal
Similarly while transferring or withdrawing you will need the TAG along with the wallet address from your destination wallet. But, as we wrote above the TAG may not always be required (as in the case of deposits onto CBANX).
We hope this little tutorial has been helpful?
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Thank you,
CBANX Support Team