Testnet

Blockchains such as Bitcoin (BTC) and Ethereum (ETH) have a primary main blockchain called a mainnet and a testing sandbox secondary blockchain called a testnet. Mainnets are the actual public ledgers which hold the real accounts with real cryptocurrency for real human users. Testnets are used by software developers to test out dApps, smart contracts, and new service features of the blockchain. For example, on Ethereum there is a testnet smart contract that serves as a free faucet that mints and emits free “test ETH”. Ethereum test ETH is used by Ethereum testnet developers to function test all aspects of Ethereum’s future growth.