A credit card allows you to pay for your expenses without bothering about availability of money at the time of payment. The credit card company pays for you and later sends a statement every month providing details of the transactions. You can then, pay the credit card company by check. Visa and Master Card are the most widely accepted credit cards.

A Debit card is almost like a check, since it allows you to spend from your available sources only. The banks where you have an account, generally issue this.

Usually a period of 6 months stay in the US is also an important criteria e.g. at least 6 months stay is essential to be considered eligible for a Credit card. The easiest to get is an American Express Card. They ask for a letter from the employer regarding salary status etc. once the initial application is verified. Most Credit cards offer other benefits like mileage accumulation in airlines, rental car insurance coverage etc.