A Layer-0 blockchain is often considered a base layer that Layer-1 blockchains and Layer-2 scaling solutions are integrated with. Though the exact classification of a Layer-0 blockchain can be ambiguous, the main purpose of a Layer-0 is to facilitate the creation of an ecosystem of interoperable blockchain networks that work together simultaneously. As such, Polkadot and Cosmos are often considered Layer-0 blockchains because their networks only serve to facilitate the security, connectivity, and interoperability of blockchains built on top of their respective platforms. Although numerous Layer-1 platforms such as Ethereum, Avalanche, Solana, and others fulfill some of these purposes by connecting many blockchains together, they are not considered Layer-0 networks.
