The virtual currency was defined in 2012 by the European Central Bank as a "type of unregulated digital money, which is issued and usually controlled by developers, used and accepted among members of a specific virtual community." It was briefly defined by the U.S. Department of the Treasury in 2013 as "a medium of exchange that functions as a currency in some environments, but does not have all the characteristics of real currency." The main feature of a virtual currency according to these definitions is the lack of legal tender status.