The currency of Armenia is the Armenian Dram (AMD). US Dollars, Euro and Russian Roubles are widely used and can be easily exchanged. The number of ATMs/bancomats in Yerevan is steadily growing and finding one nearby shouldn't be difficult. Outside the capital however you will need to carry enough local currency.  Both Western Union and Moneygram operate in Armenia, and almost all banks can send and receive foreign currency abroad via the SWIFT network. Visa and Mastercard are increasing in acceptance and many higher-end shops, restaurants and hotels accept credit card payments - however do not assume that all establishments will accept credit cards and do check beforehand.