A scalable, interoperable & secure network protocol for the next web

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Any type of data across any type of blockchain

Polkadot is a network protocol that allows arbitrary data—not just tokens—to be transferred across blockchains.

This means Polkadot is a true multi-chain application environment where things like cross-chain registries and cross-chain computation are possible.

Polkadot can transfer this data across public, open, permissionless blockchains as well as private, permissioned blockchains.

This makes it possible to build applications that get permissioned data from a private blockchain and use it on a public blockchain. For instance, a school's private, permissioned academic records chain could send a proof to a degree-verification smart contract on a public chain.

Network structure

Parachains: application-specific blockchains

Parachains are the parallelizable blockchains (“para-chains”) that comprise the Polkadot network. Each parachain can have a unique architecture that best suits its application. Parachains are also used to parallelize transactions and achieve scalability. Parachains are connected and secured by the relay chain.

Relay chain: connects and validates parachains

The relay chain connects the components of the Polkadot network. It provides security to parachains and relays messages between them, as well as bridge chains. The messages can be transactions or any arbitrary data.

Bridges chains: connect Polkadot to external blockchains

Bridges are special parachains that allow communication to independent blockchains that are not secured by Polkadot's relay chain and instead use their own security, like Bitcoin or Ethereum.

Network roles

Validators: produce relay chain blocks

Validators are staked full nodes that are responsible for verifying and adding blocks to the relay chain. Validators receive and verify potential parachain blocks from collators and include valid parachain block headers in the relay chain.

Collators: bundle transactions on parachains

Collators bundle (or collate) transactions on the parachain they monitor into blocks, and send a proof of this block to validators. Collators can also act as fishermen.

Nominators: nominate validators

Nominators put up stake and select validators to stake on their behalf. When a nominator's chosen validator is rewarded or punished, the nominator receives a corresponding reward or punishment.

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Built with the best technology

Polkadot’s relay chain is built with Substrate, a blockchain-building framework that is the distillation of Parity Technologies’ learnings building Ethereum, Bitcoin, and enterprise blockchains.

Polkadot’s state machine is compiled to WebAssembly (Wasm), a super performant virtual environment. Wasm is developed by major companies, including Google, Apple, Microsoft, and Mozilla, that have created a large ecosystem of support for the standard.

Polkadot’s networking uses libp2p, a flexible cross-platform network framework for peer-to-peer applications. Positioned to be the standard for future decentralized applications, libp2p handles the peer discovery and communication in the Polkadot ecosystem.

The Polkadot runtime environment is being coded in Rust, C++, and Golang, making Polkadot accessible to a wide range of developers.

Processing transactions in parallel

Parachains are specialized blockchains that connect to Polkadot. They will have characteristics specialized for their use cases and the ability to control their own governance.

Interactions on parachains are processed in parallel, enabling highly scalable systems.

Transactions can be spread out across the chains, allowing many more transactions to be processed in the same period of time.

Current method:
Single transaction

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Polkadot method:
Multi parallelized transactions

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A better security model

In both Proof-of-Work and Proof-of-Stake systems, blockchains compete with each other over resources to secure their networks, and blockchains are easily attacked until they develop a significant community to support their network.

Polkadot takes a different approach by letting blockchains pool their security, which means that the blockchains' security is aggregated and applied to all.

By connecting to Polkadot, blockchain developers can secure their blockchain from day one.

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Transparent on-chain governance

Updates to the protocol happen fork-free via transparent on-chain voting, so protocol development never stalls due to the lack of a clear process. The relay chain uses a sophisticated governance mechanism that is designed to establish a transparent, accountable and binding process for resolving disputes and upgrading the network.

DOT tokens are used to participate in governance decisions, including tabling proposals, voting, and bonding.

Parachains are free to design their own governance mechanisms, allowing for maximum freedom without affecting other parachains.

Learn more about Polkadot’s governance
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GRANDPA: a trustworthy consensus algorithm

Polkadot uses its original GRANDPA (GHOST-based Recursive Ancestor Deriving Prefix Agreement) consensus for a more secure and resilient network.

Under good network conditions, GRANDPA can finalize blocks nearly instantly. Under bad network conditions, like a network partition, GRANDPA can finalize large quantities of blocks (theoretically millions) at once when the partitions resolve.

Learn more about GRANDPA.

Roadmap

Polkadot development is on track to deliver the most robust platform for interoperability, security, scalability, and innovation. Polkadot is aiming to launch the genesis block by the end of 2019 with one relay chain and several parachains. Thereafter the network will ramp up to about 100 parachains.

  • 2018, June
    POC-2

  • Oct
    POC-3
    Final Consensus
    GRANDPA

  • 2019, Jan

  • Apr
    POC-4
    Final Staking
    Algo


  • Polish & Optimization


  • POC-5
    Interchain Message Passing
    BABE Block Production
    Parachain Auction Module


  • 1.0 Release Candidate 1


  • 1.0 RCL
    1.0 Final


  • Genesis

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What are teams building on Polkadot? Just a few examples:

Smart contract chains with WebAssembly smart contracts (Edgeware, Charred Cherry testnet)

Data curation networks that connect all file storage chains into curated data sets (Ocean Protocol)

Oracle chains that make off-chain data available to all contracts on the Polkadot network (ChainLink)

Identity chains that link accounts to a persistent identity and enable access to other parachains through fewer accounts (Speckle OS)

Financial chains that allow you to hold all your assets in one portfolio, including via bridges to Bitcoin, Ethereum, Bitcoin Cash, Litecoin and ZCash (ChainX, Katallassos)

Internet of Things chains that set IoT standards for machine-to-machine communication (MXC Protocol)

Zero Knowledge privacy chains, or bridges to existing ZK-snarks chains (e.g. Zerochain)

File storage chains that incentivize storing data on-chain

Payments chains with lightning-fast transactions (Blink Network)

Bridge to Ethereum, allowing Ethereum smart contracts to interact with the Polkadot network

Want to get started? Build on Polkadot