During a transaction the confidential Primary Account Number (PAN) is replaced with a generic Token:
Near Field Communications (NFC)-enabled purchases at the physical point of sale (also called "contactless communication" because buyers wave their phones or tablets over NFC compatible devices) and purchases transacted via an app, known as "In-App" or mobile purchases, use tokenization. In the future, tokenization will also be used for e-commerce purchases made through browser-based applications.
Fiserv has enhanced internal systems and processes to support tokenized payment transactions through existing technology and standard methodology. Fiserv-processed Issuers can participate in tokenization without making system changes, and account/core processors can continue to use existing card and transaction processing logic.