The Stylus testnet is designed for efficient smart contract creation using languages like Rust, C, and C++, leveraging Arbitrum's Nitro technology and EVM equivalence. This testnet facilitates remarkable speed and low gas fees for smart contracts, along with full interoperability between Solidity and Stylus contracts. However, the Stylus testnet will be deprecated once Stylus comes out of beta and is enabled on the Sepolia testnet​​. Each of the Arbitrum blockchains serves specific purposes within the broad Arbitrum ecosystem, from enabling scalable, cost-effective dApp deployment to providing risk-free testing environments for developers. They exhibit a unique blend of technologies and protocols that contribute to Arbitrum's goal of enhancing Ethereum's scalability and usability.