The Stacks Mainnet transacts in STX and is used for production apps and smart contracts.
A separate blockchain from the Stacks mainnet analogous to a staging environment. It's a network used by developers to test apps, smart contracts, or changes to the protocol in a production-like environment.
The Nakamoto Testnet allows developers to operate in a stable environment that closely resembles Mainnet.
Stacks client maintained by the foundation.