What is Kusama?

The co-founder of Kusama is Gavin Wood, the same person who co-founded the Polkadot. Gavin stated that Kusama is like a cousin to Polkadot, but with more wild personalities. The technical foundations of both networks are mostly identical. Whereas Polkadot is considered the main network that is more stable and mature, Kusama is the Testnet built for developers who prefer speed. Also, new update for Polkadot will be tested on Kusama first, hence the slogan “Polkadot's Wild Cousin.”