Polkadot Wiki

Polkadot Wiki

  • Get Started
  • Learn
  • Build
  • Maintain
  • Kusama
  • Contribute
  • Languages iconEnglish
    • Русский
    • 中文
    • Help Translate

›Basics

General

  • Getting Started
  • Claims
  • Redenomination of DOT
  • Grants
  • Thousand Validators Programme
  • Polkadot Ambassador Programme
  • Research Pages
  • Community
  • Contributing
  • Contributors
  • Glossary
  • Using ENS with DOT/KSM accounts
  • Ledger Application
  • How to Protect Yourself from Scams
  • Frequently Asked Questions (FAQs)

Learn

  • Polkadot Launch Phases
  • Basics

    • Architecture
    • Polkadot Accounts
    • Account Generation
    • Backing up and Restoring Accounts
    • DOT
    • Security of the network
    • Polkadot Consensus
    • Nominator
    • Validator
    • Collator
    • Governance
    • Identity
    • How to transfer Balances
    • Transaction Fees
    • Polkadot Host (PH)
    • Treasury
    • How to use W3F Registrar

    Parachains

    • Parachains
    • Parathreads
    • Bridges
    • Parachain Slots Auction
    • Parachain Crowdloans

    Advanced

    • Staking
    • Proxy Accounts
    • Availability and Validity
    • Randomness
    • Cross-chain Message Passing (XCMP)
    • SPREE
    • WebAssembly (Wasm)
    • Sequential Phragmén Method
    • Simple Payouts

    Cryptography

    • Cryptography Explainer
    • Polkadot Keys

    Polkadot Comparisons

    • Comparing Polkadot and Kusama
    • Ethereum 2.0
    • Cosmos
    • Dfinity
    • Other comparisons

Build

  • Builder's Portal
  • Development Guide

    • Polkadot Builders Starter's Guide
    • Parachain Development Kits (PDKs)
    • Parachain Implementer's Guide
    • Cumulus
    • Building Parachains on Rococo
    • Smart Contracts
    • Oracles
    • Polkadot Wallets

    Integration Guide

    • Integration Initiation
    • Polkadot Protocol
    • Node Management
    • Node Interaction
    • Transaction Construction

    Tools

    • Tool Index

    Resources

    • Hackathon

Maintain

  • Network Maintainers
  • Parameters
  • Nodes and Dapps

    • Set up a Full Node
    • Networks
    • Set up Secure WebSocket for Remote Connections
    • Resolving Errors

    Nominator Guides

    • How to Nominate on Polkadot
    • Unbonding and Rebonding

    Validator Guides

    • How to run a Validator on Polkadot
    • Validator Payout Overview
    • Using systemd for the Validator Node
    • Secure Validator
    • How to use Polkadot Secure Validator Setup
    • Set Up a Sentry Node
    • How to Upgrade Your Validator
    • Monitor your node
    • How to Chill

    Governance Guides

    • Participate in Democracy
    • Join the Council
    • Voting for Councillors
Edit

Architecture

Polkadot is a heterogeneous multichain with shared security and interoperability.

Relay Chain

The Relay Chain is the central chain of Polkadot. All validators of Polkadot are staked on the Relay Chain in DOT and validate for the Relay Chain. The Relay Chain is composed of a relatively small number of transaction types that include ways to interact with the governance mechanism, parachain auctions, and participating in NPoS. The Relay Chain has deliberately minimal functionality - for instance, smart contracts are not supported. The main responsibility is to coordinate the system as a whole, including parachains. Other specific work is delegated to the parachains, which have differing implementations and features.

Parachain and Parathread Slots

Polkadot can support a number of execution slots. These slots are like cores on a computer (a modern laptop may have eight cores, for example). Each one of these cores can run one process at a time. Polkadot allots these slots using two subscription models: parachains and parathreads. Parachains have a dedicated slot (core) for their chain and are like a process that runs constantly. Parathreads share slots amongst a group, and are thus more like processes that need to be woken up and run less frequently.

Most of the computation that happens across the Polkadot network as a whole will be delegated to specific parachain or parathread implementations that handle various use cases. Polkadot places no constraints over what parachains are able to do besides that they must be able to generate a proof that can be validated by the validators assigned to the parachain. This proof verifies the state transition of the parachain. Some parachains may be specific to a particular application, others may focus on specific features like smart contracts, privacy, or scalability — still others might be experimental architectures that are not necessarily blockchain in nature.

Polkadot provides many ways to secure a slot for a parachain slot for a particular length of time. Parathreads are part of a pool that shares slots and must win auctions for individual blocks. Parathreads and parachains have the exact same API; their difference is economic. Parachains will have to reserve DOT for duration of their slot lease; parathreads will pay on a per-block basis. Parathreads can become parachains, and vice-versa.

Shared Security

Parachains connected to the Polkadot Relay Chain all share in the security of the Relay Chain. Polkadot has a shared state between the Relay Chain and all of the connected parachains. If the Relay Chain must revert for any reason, then all of the parachains would also revert. This is to ensure that the validity of the entire system can persist and no individual part is corruptible.

The shared state makes it so that the trust assumptions when using Polkadot parachains are only those of the Relay Chain validator set, and no other. Since the validator set on the Relay Chain is expected to be secure with a large amount of stake put up to back it, it is desirable for parachains to benefit from this security.

Roles

Validators

Validators, if elected to the validator set, produce blocks on the Relay Chain. They also accept proofs of valid state transition from collators. In return, they will receive staking rewards.

Collators

Collators are full nodes on both a parachain and the Relay Chain. They collect parachain transactions and produce state transition proofs for the validators on the Relay Chain. They can also send and receive messages from other parachains using XCMP.

Nominators

Nominators bond their stake to particular validators in order to help them get into the active validator set and thus produce blocks for the chain. In return, nominators are generally rewarded with the portion of the staking rewards from that validator.

Whiteboard Series

For a video overview of the architecture of Polkadot watch the video below for the whiteboard interview with W3F researcher Alistair Stewart:

Last updated on 1/15/2021 by joe petrowski
← Polkadot Launch PhasesPolkadot Accounts →
  • Relay Chain
  • Parachain and Parathread Slots
  • Shared Security
  • Roles
    • Validators
    • Collators
    • Nominators
  • Whiteboard Series
General
  • About
  • FAQ
  • Contact
  • Build
  • Grants and Bounties
  • Carrers
Technology
  • Technology
  • Token
  • Telemetry
  • Substrate
  • Whitepaper
  • Lightpaper
Community
  • Community
  • Documentation
  • Brand Assets
  • Blog
  • Element Chat
  • Medium

Subscribe to the newsletter to hear about Polkadot updates and events.

Polkadot Network
  • © 2021 Web3 Foundation
  • Impressum
  • Disclaimer
  • Privacy
  • Cookie Settings
  • Testnet disclaimer