A wallet shows a large balance, but the network selector says testnet. That balance is part of a testing environment, not evidence that someone has received the same amount of spendable mainnet currency.
The Ethereum network documentation distinguishes mainnet from test networks used for development. It notes that testnet ETH is intended to have no real value, while acknowledging that scarcity has sometimes produced markets for particular test tokens. That caveat does not make a test balance equivalent to mainnet ETH.
Keep the environment visible
When following a tutorial, confirm the network, contract address and explorer associated with it. Use a dedicated test wallet rather than casually mixing experiments with an account holding real assets. Never provide a recovery phrase to a faucet or tutorial site.
Label screenshots and demonstrations clearly. An image of a successful test transaction can explain a workflow, but it should not be presented as a real payment, investment return or proof of customer activity.
Test success has limits
A contract call completing on a test network can show that a particular interaction worked under those conditions. It does not establish that the contract is secure, that real-market liquidity exists or that production behaviour will be identical.
For an illustrative development note, record the network, software version, contract address, transaction identifier and the specific behaviour tested. “Transfer succeeded” is more useful when it says what was transferred, between which test accounts and under which expected conditions.
Public test networks can change or retire. Use current official documentation to select the environment and obtain test resources. An old tutorial may point to a network that is no longer supported.
Before any production deployment, use a separate review and release process appropriate to the application. Test tokens make experimentation less financially consequential; they do not remove the need to protect credentials, inspect code and distinguish a demonstration from a claim about real-world value.