Banks mainly issue credit cards using the format Visa, Mastercard and Discover.
These three types of cards are accepted throughout the world.
As well as making purchases you can use these cards at a cash machine ( ATM ) to give you a cash advance. Please be careful though as some card issuers charge extra for this service.
Which one you should choose is a completely personal decision. In the UK all three are readily accepted. Only when you travel abroad mainly to Europe do you see some problems arising as to which to use.
For example in France, almost any bank or cash machine (if you have a 4-digit PIN) can give you a cash advance on Visa but only a few banks and cash machines can give you a Mastercard cash advance.