Tokenization is the most powerful concept being used as per PCIDSS in credit cards domain to mask card number. There are two methods how tokenization works. The differences explained in audio podcast for Vault based and Vault-less methods.
In Credit cards domain each transaction, Sale, Refund , Reversal will generate ISO 8583 messages. This post explained format of these messages.
Try to understand Digital wallets vs Credit or Debit cards. The wallets have lot convenient and benefits compared to carry physical cards. Read more with examples.
Popular credit card payment processors across the world awesome list
