Contrary to popular belief, Visa, Mastercard and the like are not types of credit card, but rather payment processing networks. These networks process credit and debit card transactions, verify them with your card issuer, and accept or decline them based on your available funds on behalf of the merchant. The merchant pays a processing fee for this service, which is how the networks make their money.
When you use your credit card or debit card, your payment system (e.g. Mastercard) connects the point of payment to your bank's credit card department. So when you go to the supermarket, for example, and use your credit card at the till, Mastercard will be the one that checks with your issuer whether or not there's enough money in your account to pay for your items.
There are four main payment networks: Mastercard, Visa, American Express and Discover. Mastercard and Visa are available in more than 150 countries, and, out of the four, are the most widely accepted – it's also very rare for one to be accepted but not the other. American Express comes in third for rate of acceptance, partly because it has a higher processing fee than Visa or Mastercard, while Discover is the least widely accepted of the four. When travelling, it might be worth checking in advance whether or not your card will be accepted in your country of choice. It would also be a good idea to find out whether card payment is widely accepted or whether cash is preferred.
Be aware that it is not the payment networks that determine what your credit card offers in terms of fees, charges and so on, or the terms and conditions of your contract – these are all set by your issuer. That said, all of the networks offer reward schemes of their own – for example, fuel rewards schemes or airport lounge access, and there are a few differences in the benefits offered by Mastercard, Visa, American Express and Discover.
With more and more purchases being made online, many credit cards have introduced extra security measures to protect you when paying for items or services over the internet. Visa's version, Visa Secure and Mastercard Identity Check work in much the same way to protect you when buying online. They work by sending a code to your phone if we need to check it’s you. We’ll ask you to choose which phone number we send it to, then prompt you to enter the code to complete the payment. This adds an extra layer of security to your online purchases.