Kusama is a permissionless network which aims to become a testing ground for experiments with significant changes on Polkadot.
A key difference between Kusama and Polkadot is that Kusama has modified governance parameters that allow for faster network upgrades, with seven days to vote on referendums and eight days to implement those upgrades after a vote.
The Relay Chain is the central chain of the Kusama network. All validators of Polkadot are staked on the Relay Chain.
The Parachains are parallel chains that connect to the Relay Chain and are maintained by their validators, called Collators.
Kusama uses the KSM tokens for network operations. KSM serves multiple purposes such as:
Governance: Where participants can manage protocol updates and fixes.
Staking: Where the tokens are staked to ensure the network remains secure, as good validators are rewarded, and bad actors lose their stake.
Bonding: Where new parachains are supported by bonding tokens.
Fees: For ferrying messages across parachains.