Testnet is, as the name implies, for testing features of the blockchain without spending 'real' semux.
It allows developers of tools and wallets to integrate and test features without risk.
You can connect to the testnet via the following command
./semux-gui.sh --network testnet
- Testnet faucet: https://www.semux.org/testnetfaucet
- Testnet explorer: https://testnet.semux.info/
If you prefer using a local testing blockchain, see Devnet.