Polkadot is an open source sharding multi-chain protocol that combines multiple blockchain platforms into a unified and scalable network, not only tokens, any data or asset types can be transmitted across chains, enabling various Blockchains can interoperate. This interoperability aims to establish a fully decentralized proprietary network controlled by its users and to simplify the creation of new applications, institutions and services.
The Polkadot protocol connects public chains, private chains, permissionless networks, oracles, and any network that may emerge in the future, allowing these independent blockchains to trustlessly share information and transactions through the Polkadot relay chain.
In simple terms, Polkadot is a "blockchain of blockchains" that allows many different types of chains to work and interact securely within the same ecosystem.
Polkadot is a heterogeneous multi-chain network, which means it connects various blockchains designed for a specific purpose into a single ecosystem. These different layer 1 blockchains are called parachains because of the way they process transactions in parallel, and are linked together by the Polkadot relay chain.
Polkadot has four core components:
Relay Chain: The "heart" of Polkadot, helping to create consensus, interoperability and shared security across networks of different chains;
Parachains: independent chains that can have their own tokens and are optimized for specific use cases;
Parathreads: similar to parachains, with flexible connections based on a pay-as-you-go economic model;
Cross-chain bridge: Allows parachains and parathreads to connect and communicate with external blockchains such as Ethereum.
Polkadot uses Nominated Proof of Stake (NPoS), adding the roles of validators and nominators to maximize the security of the chain. Four roles and roles in Polkadot NPoS:
Validators secure the relay chain by staking native tokens (DOT). If elected to the active set, they verify proofs of proofreaders on parachains, participate in consensus with other validators, and produce blocks on the relay chain. In return, they get staking rewards.
Nominators also contribute to the security of the network by staking their DOTs to support trusted validators, helping them enter the active validator set. In return, nominators typically receive a portion of the staking reward from that validator.
Collators collect parachain transactions and generate proofs for validators on the relay chain. They can also send and receive messages from other parachains using the Cross-Chain Messaging Protocol (XCMP).
Fishermen monitor the network and report bad behavior to validators. Any parachain full node can play the role of fisherman.
Polkadot's native DOT token serves three purposes: keeping the network running and secure, staking DOT to connect the chain to Polkadot as a parachain and holders' voting rights in network governance. DOTs are inflationary, which means that unlike Bitcoin, there is no maximum amount of DOTs. The inflation rate is not fixed: it is designed to be 10% in the first year. The generated DOTs are used to reward validators, and the rest will go to the treasury.