Mainchain

A mainchain, or main chain, is the primary blockchain in a system made up of several connected chains. It holds the native coin and serves as the final record that sidechains, child chains and some layer-2 networks rely on: assets are locked on the mainchain when they move to a connected chain, and released again when they return. In this sense, Bitcoin is the mainchain for proposals such as drivechains, and Ethereum is the mainchain for rollups and older Plasma-style systems. The term is close to layer-1 blockchain but describes a relationship rather than a category: a chain is a mainchain relative to the chains that depend on it. It differs from mainnet, which means the live production version of a network as opposed to a test network. "Main chain" can also mean the branch nodes follow after a fork.