Testnet

A testnet is a parallel copy of a blockchain network that runs the same protocol rules with coins that have no market value, so developers can deploy and break things without risking funds. Test coins are handed out by faucets rather than bought, which is why a testnet balance is worthless by design and any offer to buy one is a scam signal. Ethereum has retired several testnets over the years and currently points developers at networks such as Sepolia and Holesky, each aimed at a different audience. Testnets also serve as rehearsal grounds for protocol upgrades: a fork is usually activated on test networks first so client bugs surface before real value is at stake.