A destination tag is 9-digit numbers designated to each Ripple (XRP) account. It is used to identify the receiver in a Ripple transaction. When sending XRP, you need to provide the following information:
- Wallet address you are going to send your XRP to
- Destination tag
The tag must be specified when transferring XRP to Genesis Block Portal. The destination may or may not be required when sending XRP to external wallets depending on the policies of the exchange. Yet, please note that most exchanges require destination tag.