Bitcoin is the first cryptocurrency that was introduced by the year 2009 by an unknown person or group named by Satoshi Nakamoto still his identity is remained a mystery .The  .Bitcoin is a peer to peer electronic cash system The Block chain technology   verifies the transaction records of.Bitcoin.. Even though bitcoin was introduced by 2009 it was only mined and  not traded till 2010 .By 2010 somebody sold Bitcoin for buying pizza and that was the first trading, from that transaction on wards  the popularity of Bitcoin increased  and the idea of decentralization inspiring  other alternative crypto currencies to appear.