Kusama CC1 represents an initial release of Polkadot, designed to be a testing ground for governance, staking, and sharding. It serves as a prelude to the mainnet launch of Polkadot, allowing developers to build and deploy Parachains under real economic conditions.

CC2 introduces a new chain compared to CC1, incorporating important fixes. User accounts remain unchanged as all CC1 transactions are included in the CC2 chain.

CC2 undergoes a runtime upgrade to prepare for a switch to a Nominated Proof-of-Stake system, replacing its Proof-of-Authority predecessor. Along with this update, the Council elections module is introduced, allowing participants to elect other stakeholders to the Kusama Council - the network's on-chain governance system. Additionally, other new features are introduced in the release, v0.6.18.

CC3 introduces on-chain authority discovery, a revamp of the network's governance system, and a move to prefixed storage mappings. Additionally, the new decentralized, on-chain governance system successfully passed Referendum 4, resulting in the removal of Sudo requirements and enabling KSM token transfers.

During a runtime upgrade to version 1034, Kusama faced a naming issue that caused the chain to become unresponsive. To rectify the situation, the Polkadot team issued updates to revert the chain, reject the faulty upgrade, and accelerate the chain's progress to prevent it from lagging behind. The canary network returned to normal operating speed on Jan. 12, eight days after the failed runtime upgrade.