"Operations"

Visa offers through its issuing members the following types of cards:
Debit cards (pay from a checking / savings account)
Credit cards (pay monthly payments with interest)

Prepaid cards (pay from a cash account that has no checkwriting privileges)

Visa operates the PLUS automated teller machine network and the Interlink EFTPOS point-of-sale network, which facilitate the "debit" protocol used with debit cards and prepaid cards. They also provide commercial payment solutions for small businesses, midsize and large corporations, and governments.
Operating regulations
Visa has a set of rules that govern the participation of financial institutions in its payment system. Acquiring banks are responsible for ensuring that their merchants comply with the rules.
Rules address how a cardholder must be identified for security, how transactions may be denied by the bank and how banks may cooperate for fraud prevention, and how to keep that identification and fraud protection standard and non-discriminatory. Other rules govern what creates an enforceable proof of authorization by the cardholder.
The rules prohibit merchants from imposing a minimum or maximum purchase amount in order to accept a Visa card and from charging cardholders a fee for using a Visa card. In ten U.S. states, surcharges for the use of a credit card are forbidden by law but a discount for cash is permitted under specific rules. Some countries have banned the no-surcharge rule, most notably the UK and Australia and retailers in those countries may apply surcharges to any credit-card transaction, Visa or otherwise.
Unlike MasterCard, Visa does permit merchants to ask for photo ID, although the merchant rule book states that this practice is "discouraged". As long as the Visa card is signed, a merchant may not deny a transaction because a cardholder refuses to show a photo ID.