Polkadot is a network designed to join the dots with all other networks. It's commonly referred to as a multi-chain network, because it can join networks together, unlike networks like Bitcoin, which operates on its own.
Its ultimate aim is to act as a framework for all blockchains that opt-in, a bit like how HTML allows sites, browsers, and servers to interact with each other. The idea is to take care of messy and costly cryptocurrency mining processes (including validation of transactions and security protocols) and enable developers to focus on creating dapp and smart contract functionality.
What is Kusama?
Kusama is a public pre-production environment for Polkadot, one that allows any developer to experiment and test new blockchains or applications before releasing them on this network.In this way, it can be said Kusama acts as a kind of sandbox for developers looking to test early versions of Polkadot projects, but with real cryptocurrency traded on an open market.Official Polkadot upgrades are also tested on Kusama before their release.
Because its primary use case is to facilitate testing, Kusama attempts to give developers more flexibility while they finalize the design of their Polkadot projects. In turn, Kusama offers looser rules than Polkadot, including less stringent governance parameters.
Elsewhere, Kusama mimics most of Polkadot’s major design features. For example, Kusama uses two types of blockchains – a main network, called a relay chain, where transactions are permanent, and user-generated networks, called parachains.Parachains can be customized for any use and leverage the main relay chain for security.
A potential advantage of starting a project on Kusama is that it allows Polkadot projects to build a user base and gain traction in the community before the official launch.
What the two networks have in common?
Kusama was released as an early version of the same code to be used in Polkadot, which means they share the same underlying architecture: a multichain, heterogeneously-sharded design based on Nominated Proof of Stake (NPoS). Both networks also share key innovations like on-chain governance, hot-swappable runtimes for forkless, on-chain upgrades, and Cross-Chain Message Passing (XCMP) for interoperability. Governance on both Polkadot and Kusama is designed to be decentralized and permissionless, giving a say in how the network is run to everyone who owns the native token (DOT for Polkadot, KSM for Kusama). Therefore, over time the networks will evolve independently, converging or diverging according to the decisions of their respective communitie.
Both networks also have different circulating supplies.
The first key technical difference between Polkadot and Kusama is that Kusama has modified governance parameters that allow for faster upgrades. Kusama is up to 4 times faster than Polkadot, with 7 days for token holders to vote on referendums followed by an enactment period of eight days, after which the referendum will be enacted on the chain. This means stakeholders need to stay active and vigilant if they want to keep up with all the proposals, referenda, and upgrades, and validators on Kusama often need to update on short notice.
On Polkadot, votes last 28 days followed by an enactment period of 28 days. This does not mean that the Kusama blockchain itself is faster, in the sense of faster block times or transaction throughput (these are the same on both networks), but that there's a shorter amount of time between governance events such as proposing new referenda, voting, and enacting approved upgrades. This allows Kusama to adapt and evolve faster than Polkadot.
Teams wishing to run a parachain need to bond tokens as security. The bonding requirement on Kusama is likely to be lower than on Polkadot.
Polkadot is and always will be the primary network for the deployment of enterprise-level applications and those that entail high-value transactions requiring bank-level security and stability. The initial use case for Kusama is as a pre-production environment, a “canary network”. Building on Kusama first allows teams to test things out in a live, fully decentralized, and community-controlled network with real-world conditions and lower stakes in the event of problems or bugs than on Polkadot.
Many projects will maintain parachains on both networks, experimenting and testing new technologies and features on Kusama before deploying them to Polkadot. Some teams will decide just to stay on Kusama, which is likely to be a place where we see some exciting experimentation with new technologies going forward. Projects that require high-throughput but don’t necessarily require bank-like security, such as some gaming, social networking, and content distribution applications, are particularly good candidates for this use case.
Ultimately, Kusama and Polkadot will live on as independent, standalone networks with their own communities, their own governance, and their own complementary use cases, though they will continue to maintain a close relationship, with many teams likely deploying applications to both networks. In the future, we’re also likely to see Kusama bridged to Polkadot for cross-network interoperability. Web3 Foundation remains committed to both networks going forward, providing crucial support and guidance to teams building for the ecosystem.