Visa cards work by taking the place of cash in a purchasing transaction with a retailer, according to Visa. The cardholder presents the card or the card number to the retailer, who then charges the price of the product purchased to the card acquirer, which is the retailer's bank. The acquirer pays the retailer the funds charged, then charges the financial institution that issued the card to the cardholder. The issuer then collects the charged amount from the cardholder.
Before use, the cardholder must make sure that the retailer accepts Visa as a form of payment. To accept Visa, the retailer must have an existing contract with a Visa acquirer, as Visa explains. The acquirer ensures that the retailer is paid regardless of whether the cardholder actually pays the card issuer or not.
The card issuer also has a contract with Visa and is ultimately responsible for seeing that the acquirer is paid, notes Visa. This places the burden on the issuer to determine if the cardholder is capable of paying for purchases.
For a debit Visa card, the funds are deducted from the cardholder's debit account, explains Visa. For a Visa credit card, the cardholder is billed the transaction amount.