MasterCard was originally started in 1966 in the wake of their primary competitor: Visa. After changing hands multiple times, the company went public in 2006 and currently represents millions of card holders. Today the only modern credit card company that can boast larger numbers than MasterCard is still Visa, their original rival. This deposit option is available for all US players, but you may have some trouble processing the deposits depending upon the exact circumstances.
Typically MasterCard deposits are referring to the use of your MasterCard credit card, but there is one other possibility. If you'd rather not use your credit card online for any reason (security, discretion, etc...) you can always purchase pre-paid MasterCard gift cards. These are often available in local grocery/convenience stores and can be bought with cash or credit. These gift cards look just like normal credit cards and can be used for casino deposits in the exact same way.
How To Use MasterCard
MasterCard deposits are extremely simple. You just enter your name and credit card information, and your deposit should be completed instantly. Depositing using this option is just like using a credit card anywhere else on the Internet. Also, since MasterCard has such a solid reputation, this is a great deposit option for anybody who is concerned about privacy and security. Between state of the art encryption and advanced account protection, your money is safe when using MasterCard.
On occasion, some American players do have a difficult time making deposits with their MasterCard credit cards. If your card is rejected when depositing online, you may have better luck if you call your casino's help line and speak directly with an operator. After calling in, if you still cannot complete your MasterCard deposit, you may want to use a US friendly eWallet to get funds from your MasterCard account into the online casino of your choice.