Basic information:
Accounts in the XRP Ledger are identified by an address in the XRP Ledger's format (25-35 characters, starting with an "r", case-sensitive).
For example
XRP address: rXieaAC3nevTKgVu2SYoShjTCS2Tfczqx
Destination Tag: 153214622
>> View infographic:
IMPORTANT NOTE: Institutions who send and receive value on behalf of many users can use Destination Tags to distinguish payments from and to their customers while only using one (or a handful) of accounts in the XRP Ledger. (source: www.xrpl.org)