What is ethereum classic?

Ethereum Classic (ETC) is a cryptocurrency that emerged as a result of a split in the Ethereum blockchain. The story behind Ethereum Classic dates back to 2016 when the Decentralized Autonomous Organization (DAO), a smart contract and investment fund on the Ethereum platform, suffered a significant security vulnerability.
In an attempt to recover the funds lost in the attack, the Ethereum community proposed a controversial hard fork to reverse the transactions and create a new version of the blockchain. This fork led to the creation of Ethereum (ETH), which followed the new set of rules and had the reversed transactions.
However, a portion of the Ethereum community disagreed with the idea of altering the blockchain's immutability and maintaining a "code is law" principle. This dissenting group continued to support the original, unchanged Ethereum blockchain, leading to the creation of Ethereum Classic.
So, Ethereum Classic is essentially the original Ethereum blockchain, maintaining its history without implementing the changes that were introduced in the fork that resulted in Ethereum (ETH). Despite this split, both Ethereum (ETH) and Ethereum Classic (ETC) continue to exist as separate and independent blockchain networks, each with its own set of developers, community, and ecosystem.