The increased popularity and new technologies for data storage and transmission (including that of digital money) give rise to decentralized infrastructures for payments, money transfers, and money storage with transaction costs close to zero. Crypto currencies, such as BitCoin, are part of these new technologies. Crypto currencies, as digital payment vehicles, apply cryptographic principles to achieve a well distributed, decentral and safe payment ecosystem.*
These new technologies lead to an increased acceptance by individuals of non-sovereign currencies, especially also in countries with limited international money flows or high inflation, as South America, for example. To avoid the loss of control over parts of the financial system and to secure employment, some governments have already drafted legislation to enable the issuance of private currencies in their respective country. These new, digital are viewed as a complement to the exiting monetary system. This development both softens the state monopoly for monetary policy and allows a regulation of new currency issuers.
* Source: Wikipedia article about crypto currency as of June 7, 2015