What chain is mainnet?

Excuse me, could you please clarify what you mean by "What chain is mainnet?"? In the context of cryptocurrency and blockchain technology, "mainnet" typically refers to the primary or live network of a blockchain project where real transactions take place, as opposed to a test network or testnet. Are you asking about the specific blockchain protocol or technology that a particular mainnet is built on, or are you trying to understand the difference between mainnet and other types of networks? Could you provide more context or detail so I can give you a more accurate answer?