Layer 0

Layer 0 sits underneath every individual blockchain, supplying the shared infrastructure that lets separate networks communicate instead of operating as isolated islands of data and value. Rather than processing transactions itself, a Layer 0 protocol provides the base level consensus, security, and messaging rules that Layer 1 chains plug into, somewhat like how TCP/IP underlies the internet without any single website running directly on it.

Most Layer 0 designs share three components: a coordinating main chain, application specific chains connected to it, and a communication standard that lets those chains exchange data and assets. Polkadot's Relay Chain links purpose built parachains and, following the 2024-2025 Polkadot 2.0 upgrade, allocates blockspace through an on demand system called Agile Coretime rather than one off auctions. Cosmos takes a more sovereign approach: independent "zones" built with the Cosmos SDK connect through the Inter-Blockchain Communication protocol while keeping their own validators and governance. Avalanche splits activity across its X-Chain, C-Chain, and P-Chain, and lets projects launch custom subnets for gaming, DeFi, or enterprise use.

By pushing interoperability and shared security down to the base layer, Layer 0 networks let developers launch new chains quickly without rebuilding consensus from scratch, and let users move value across ecosystems. The trade-off is a larger attack surface: the bridges and relayers connecting these chains have historically been exploited far more often than the underlying consensus layers themselves, so audits and conservative validator design matter as much as raw throughput.