All Substrate-based chains are seamlessly compatible with Polkadot, granting access to a rich, interoperable ecosystem of parachains, applications, and resources.

Key Points:

• Polkadot is a layer-0 protocol and multichain network laying the foundation for the future of Web3. Substrate is the primary blockchain SDK used by developers to create the parachains that make up the Polkadot network.

• Substrate allows you to create specialized blockchains for any use case, and was used by Parity Technologies to create Polkadot itself, which attests to its high level of performance, flexibility, and robustness.

• While Substrate can be used to build any type of blockchain, not just Polkadot parachains, connecting to Polkadot offers a multitude of benefits, including built-in security, cross-chain interoperability, and access to Polkadot’s growing ecosystem of platforms, applications, and end-users.

• Building a custom blockchain with Substrate offers greater freedom, flexibility, and optimization than building on top of a general-purpose smart-contract blockchain.

Substrate, Polkadot, and the Web3 Vision

By Gavin Wood, co-founder and former CTO of Ethereum, founder of Polkadot and Parity Technologies

Substrate strives to be the best blockchain framework in which to build your custom blockchain. Substrate is not a blockchain in itself, but akin to a blockchain SDK framework. Substrate empowers you to build beyond the capabilities of others, giving you the freedom to define your chain however you want.

Substrate & Polkadot

The relationship between the framework and the network

Substrate-based chains are easy to integrate into Polkadot or Kusama to become a parachain or parathread. Essentially, Substrate is the SDK with which you can build parachains and Polkadot is the means of securing the chains and allowing them to communicate with each other.

However, although they're synergistic, Polkadot and Substrate are not dependent on each other. Polkadot parachains can be built and maintained without ever touching Substrate (though alternative software options for doing so are currently limited) and chains built with Substrate do not need to be connected to Polkadot or Kusama. Substrate-based chains can exist as ‘solo-chains’ on an independent basis.

Greater Possibilities

The limitations of general-purpose smart-contract blockchains

Developing a new project specific to your use-case by reusing a general-purpose smart-contract blockchain forces you to inherit all of that blockchain’s design decisions, which are often made with different priorities in mind than your own.

For example, reusing the Ethereum codebase implies several limitations: having to place all of your business logic in terms of the EVM, being forced to use one of the two EVM languages, having all business logic dynamically metered, and being limited to Ethereum's transaction pool and lack of core upgradability.

The Road to Substrate

From Polkadot’s early days to the most advanced blockchain SDK

When we started building Polkadot at Parity, we considered this and knew that it would not be realistic to build such an innovative new blockchain on top of the existing Ethereum design, even if we were the ones who had designed and written it. Ethereum was simply not the right tool for the job. So we started building Polkadot as an entirely fresh blockchain project without those design constraints.

Before long, we knew that many of the components we were building for the Polkadot Relay Chain would be useful when building Polkadot’s parachains. Substrate took shape soon after when we began collecting those common components together and forming a blockchain framework around them. By leveraging the cutting edge software built for the Polkadot Relay Chain, we could provide the parachain community with the best technology for their own chains.

The Web3 vision

How Substrate relates to the broader goals of Web3

Substrate fulfils two main goals within the overall Web3 vision: it is the foundational technology that allowed us at Parity to build the Polkadot Relay Chain; and, together with the Cumulus project, it is the de facto SDK for Polkadot, allowing parachain teams to build and deploy their chains on Polkadot.

Substrate Specifics

Modularity, performance, and flexibility

All blockchains need some sort of business logic that defines (amongst other things) what transactions do. Substrate chains are no different, and business logic is provided through a modular system known as FRAME. Using FRAME, you can very easily create, compose and publish components to form your own specialist business logic.

By providing you with a true open canvas, together with practical components that can be composed, reused and published, Substrate opens up whole new worlds of design space and potential for innovation. Indeed, the fact that Substrate is the underlying blockchain framework we used to build the Polkadot Relay Chain attests to its performance and flexibility.

Decentralization & Usability

Enabling true decentralisation and usability as fundamental to the success of Web3

One chief goal of Substrate, as a core component of the Web3 vision, is to ensure true decentralization, meaning users do not need to go through intermediaries in order to use "decentralized" applications. Bitcoin started down this path with its "SPV" client technology, but for more generalistic chains and frameworks, the task is rather more complex.

For this reason, Substrate is dedicated to the use of open, well-adopted and web-literate technologies, such as Webassembly and libp2p, as well as light-client technology. Only with an enduring focus on these can we deliver browser and mobile applications with no greater a barrier to adoption than traditionally centralized applications, a critical requirement for delivering the promised independence and self-sovereignty of the Web3 vision.