Polkadot is a multi-chain network protocol that connects many specialised blockchains (“parachains”) to a central Relay Chain. The Relay Chain provides shared security, consensus and cross-chain interoperability, while parachains run in parallel and communicate using Polkadot’s cross-consensus messaging (XCM). The design targets scalability and composability across chains within one network.

In Polkadot’s architecture, parachains are application-specific chains whose blocks are produced by collators and verified by Relay Chain validators. By attaching to the Relay Chain, parachains inherit the economic security of the validator set and can exchange messages with other chains through XCM. Bridges can also link Polkadot to external networks—for example, Ethereum via Snowbridge; connectivity to Bitcoin is provided by parachains such as Interlay rather than a native light-client bridge. For operational detail on cross-chain messaging, see the dedicated XCM section.

DOT is the network’s native token on the Relay Chain. In Polkadot’s specification it underpins three core functions: governance of the protocol, staking for network security, and bonding (the mechanism historically used to add chains).

Polkadot’s resource model is evolving with “Polkadot 2.0”. Rather than leasing long-term slots, projects access Relay Chain compute via coretime (time on virtual cores). Coretime is allocated to system chains by governance and acquired by other chains on the open market.