A testnet is a version of a blockchain that is used for testing and development before new features are launched on the main network (mainnet). Testnets allow developers to build and experiment without risking real money. They often use “test tokens” that have no real-world value. Popular examples include Ethereum’s Goerli and Sepolia testnets. If you’re new to crypto development, experimenting on a testnet is a safe way to learn.