Ethereum Classic (ETC)
Ethereum Classic (ETC) is a hard fork of Ethereum (ETH). The hard fork took place on October 25, 2016, as a reaction to the reversal of a hard fork that took place on Ethereum that undid a hack to one of the smart contracts running on top of Ethereum. The hard fork was driven by the ideology that a blockchain should be immutable and, therefore, transactions should be irreversible.
How to use Ethereum Classic with Trezor
Even though Ethereum Classic is currently not integrated in Trezor Wallet (although work is in progress to change that soon), it can be safely used with certain third-party wallets and services, with the seed and private keys fully protected by the Trezor device. These include MyEtherWallet and MyCrypto. For more information about other third-party services, see Apps.