Layer 0

Layer 0 refers to the foundational framework beneath blockchains that makes it possible to create, connect, and coordinate multiple Layer 1 networks. It includes the underlying protocols and networking components that help blockchains communicate, route messages, and sometimes share security or validator infrastructure.

A Layer 1 blockchain, such as a base chain that processes transactions and runs smart contracts, typically operates as its own self-contained network. Layer 2 systems then scale a specific Layer 1 by moving some activity off-chain or into specialized execution environments. Layer 0 sits below these, focusing less on executing user transactions and more on providing the rails that support many chains.

In practice, Layer 0 can define standards for cross-chain communication, provide a hub-and-spoke or mesh network for message passing, and offer tooling so developers can launch new Layer 1 chains without reinventing core networking and consensus components.

A central goal of Layer 0 design is reducing blockchain isolation, where assets and applications are trapped on a single chain. Interoperability protocols can allow a decentralized application on one chain to interact with assets or data on another chain through standardized messaging.

Examples often cited in this context include ecosystems like Polkadot and Cosmos. Polkadot coordinates multiple specialized chains that can communicate through a common framework, while Cosmos emphasizes interoperable chains connected through shared communication standards. More broadly, Layer 0 concepts also relate to how new applications can be built to interact with established networks like Bitcoin through additional networking and protocol layers.