A mainnet, short for "main network" is used to describe the most stable and fully deployed version of a blockchain.
This is where actual cryptocurrency transactions, with real monetary value are being being broadcasted and verified through the network.
To use the Web3API BSC mainnet APIs, select the API key labelled as Mainnet (Chain ID : 56) to view and interact with the live BSC network.
In contrast to the mainnet, a testnet, short for "test network" is a blockchain protocol that is still under development, usually simulating transactions on the mainnet closely.
A testnet is useful to developers to run and troubleshoot apps, without incurring real world cost or implications. A testnet uses testnet currency, such as testnet BNB which simulates the behaviour of actual BNB on the mainnet.
Once an app has been verified to be fully functional and secure, it can be opened to users by being deployed to the mainnet.
To use the Web3API BSC testnet APIs, select the API keys labelled as Testnet (Chain ID : 97) to view and interact with the BSC testnet.