#explain-card ## Introduction - **Brief overview:** A [[Parachain|parachain]], short for "parallelized chain," is an application-specific blockchain that connects to and is secured by a central Relay Chain, most notably [[Polkadot]]'s Relay Chain or Kusama's Relay Chain. - **Importance in [[Web3]]:** Parachains enable scalability and specialization within a larger blockchain ecosystem. They allow diverse blockchains with unique features and optimizations to coexist and interoperate while benefiting from the shared security of the Relay Chain. - **Basic definition:** A Layer-1 blockchain that runs in parallel with other parachains, connected to and validated by a Layer-0 Relay Chain, forming a sharded network. ## Core Concepts - **Relay Chain Connection:** Parachains lease a slot on the Relay Chain (e.g., through auctions on Polkadot/Kusama) to connect. Once connected, their [[Block|blocks]] are validated by the Relay Chain's [[Validator|validators]]. - **Shared Security:** Parachains inherit their security from the Relay Chain. This means they don't need to bootstrap their own validator set, significantly lowering the barrier to creating a secure blockchain. - **Specialization:** Each parachain can be optimized for a specific use case (e.g., [[DeFI|DeFi]], [[NFT|NFTs]], identity, [[Smart contract|smart contracts]] in a specific language like [[EVM]] or Wasm). They can have their own governance, native tokens, and runtime logic tailored to their purpose. - **Interoperability (XCM):** Parachains within the same ecosystem (e.g., Polkadot) can communicate and exchange assets or arbitrary messages with each other using Cross-[[Consensus]] Message Format (XCM). This allows for rich cross-chain interactions. - **Collators:** Parachain maintainers, known as collators, are responsible for producing new block candidates for their parachain and submitting them to the Relay Chain validators for inclusion and finalization. - **Governance:** While security is shared, parachains typically maintain their own governance mechanisms for protocol upgrades and decision-making specific to their chain. ## Use Cases - **Application-Specific Blockchains:** Building a blockchain optimized for a particular [[DApp|dApp]] or service (e.g., a DeFi-specific chain like [[Acala]], an EVM-compatible smart contract platform like [[Moonbeam]]). - **Ecosystem Hubs:** Parachains that act as hubs for specific functionalities, like smart contract execution, asset issuance, or bridging to other networks. - **Consortium Chains:** Private or permissioned blockchains that connect to a public Relay Chain for security and interoperability. - **Experimentation (on Kusama):** Parachains on Kusama often serve as a proving ground for new technologies and economic models before potential deployment on Polkadot. ## Related Concepts (Optional) - Polkadot - [[Substrate]] (often used to build parachains)