Bitcoin

Bitcoin is a digital currency first (internet currency) with physical counterparts. The first physical Bitcoins were created by Casascius Bitcoins. Casascius Bitcoins were created by Mike Cladwell in Utah and are made of brass, silver, and gold. .

Background
Bitcoin (sign: BTC) is a decentralized digital currency based on an open-source, peer-to-peer internet protocol. It was introduced by a pseudonymous developer named Satoshi Nakamoto in 2009. Vendors are beginning to appear offering banknotes and coins denomintated in bitcoins. The first being Casascius Bitcoins, with denominations of 1 BTC, 5 BTC, 10 BTC, 25 BTC, 100 BTC, 500 BTC, 1,000 BTC, and 1,000 BTC Gold Coin.