Mainnet
The live, production version of a blockchain network where real transactions with real economic value take place. A mainnet launch represents the moment a blockchain goes from development and testing to public operation. Assets on mainnet have real market value, unlike testnet tokens which are worthless.
“Solana's mainnet launched in March 2020. Before that, developers tested on devnet and testnet. A 'mainnet launch' for a project is a major milestone signaling production readiness.”
Testnet
A separate blockchain network used for testing and experimentation that mirrors the functionality of its corresponding mainnet but uses tokens with no real monetary value. Testnets allow developers to deploy, test, and debug smart contracts in a realistic environment without risking real funds. Users can obtain free testnet tokens from 'faucets.'
Blockchain
A distributed, append-only digital ledger that records transactions across a network of computers in a way that makes it cryptographically secured and practically impossible to alter historical records. Each block contains transaction data and is linked to the previous block through a cryptographic hash, forming an immutable chain.
Layer 1
The base blockchain network that provides the foundational infrastructure — consensus, security, and data availability — upon which applications and Layer 2 solutions are built. Layer 1 blockchains process and finalize transactions on their own mainnet and have their own native cryptocurrency for gas fees.