The original Ethereum blockchain that chose not to revert the DAO hack.
Ethereum Classic is a decentralized platform that runs smart contracts: applications that run exactly as programmed without any possibility of downtime, censorship, fraud, or third party interference. Ethereum Classic is a continuation of the original Ethereum blockchain - the classic 'unforked' version; free from external interference and subjective tampering of transactions.
Ethereum Classic continues to exist and is traded on various cryptocurrency exchanges.