This refers to the process where the merchant/acquirer requests Authorisation for a card transaction. This can include any of:

• Requesting authorisation from the chip card.
• Requesting authorisation from the Issuer (or a stand-in system on behalf of the Issuer if they are not available), by sending an Authorisation Request message to Visa/Mastercard; see 0100 Message.
• Authorising the transaction locally, either at the merchant terminal or at the Acquirer. Visa/Mastercard rules will dictate when this is permitted and who would be liable if the transaction was fraudulent.