Polkadot: A Detailed Technical Impression

Hi Everyone, Didn’t we promise a detailed blog on Polkadot last week? Here is the technical impression of Polkadot Blockchain giving you a much-magnified outlook of its architecture and working philosophy. If you have missed our previous blog on Polkadot, please find it here.

To get started, let’s get back to the ideation of Blockchain. The technology of Blockchain was primarily introduced to solve the issues caused by centralization. The distributed, peer-to-peer network succeeded in eliminating the need for third parties or intermediaries in any transmission. However, it came with a downside. Each blockchain was coined in a fashion that it got dedicated to a specific functionality like banking, health care, supply chain, or any other. These blockchains thus always remained isolated, working as stand-alone applications, limiting their functional capacity.

To make it clearer, let’s consider a scenario where an online shopping application, built on blockchain, needs to avail a payment service that is provided by another blockchain.

A “web” should provide interconnection and communication between blockchains also. There are various solutions for providing interoperability between blockchain such as CosmosFusionPolkadotARK, etc. In this article, let’s dissect ”Polkadot”, the most popular one on the list.


The idea of Polkadot was first conceived in 2016 by Gavin Wood, co-founder of Ethereum. It is designed to host multiple domain-specific blockchains, providing a medium for interoperability and communication.

“ Polkadot provides a blockchain architecture that supports scalability and interoperability. It is a heterogeneous multi-chain blockchain.”


Let us see these features in detail.

Polkadot has a main chain called relay chain, which connects multiple blockchain networks. The individual blockchain networks connected to the relay chain can run in parallel and communicate with each other, thereby increasing the number of transactions processed per second (tps) and supporting interoperability. The networks connected to the relay chain are of heterogeneous nature: it may include public blockchains, private blockchains, the technology used behind each blockchain may be different. Upgrades can be applied to individual chains without affecting the working of the Polkadot system. It also provides options to build bridges for connecting already existing blockchain networks like Bitcoin, Ethereum, etc. Polkadot offers high scalability by allowing network expansion without deteriorating the performance.

Polkadot Architecture

The relay chain is the main component of Polkadot which interconnects the individual blockchains. The relay chain is responsible for security, consensus, and cross-chain interoperability. It has only minimal features which are required to coordinate the functionality of Polkadot.

Parachains are the external blockchain networks that are connected to the relay chain and run in parallel to the relay chain. They continue to exist as independent entities and their internal details are hidden from the relay chain. But the parachains should adhere to the interface specified by Polkadot in order to communicate with the relay chain and other parachains in the Polkadot network.

There are two types of nodes in the relay chain: validators and nominators. Validators are similar to miners. Validators verify the parachain blocks and participate in the consensus to create relay chain blocks. Each parachain will be assigned a specific number of validators. Validators are elected by a Nominated Proof of Stake consensus. Nominators are stakeholders who back and nominate validator candidates. Any DOT (cryptocurrency of Polkadot) holder can act as a nominator. The numbers of validators will be limited but there is no limit on the number of nominators.

Each parachain selects some of its nodes as collators. The collators create the parachain blocks and submit them to validators. Collators retain the information specific to a parachain and interact with other parachains through messages. The selection process and rewards of collators are decided by the parachains independently. Fishermen nodes of parachain perform security checks to ensure the proper functioning of parachain. Collators may also act as fishermen.

Building a block

Polkadot network deals with parachain blocks, which are specific to each parachain, and relay chain blocks which store the parachain block receipts.

Parachain selects a collator to build the parachain block. Polkadot assigns a certain number of validators to each parachain. Polkadot also selects a validator to create a relay chain block.

Collator passes the Proof of validity to validators of its parachain. Proof of validity consists of the parachain block along with some extra information required to perform the verification. Instead of including every parachain block in the relay chain, the validators create a smaller size “candidate receipt” for each valid parachain block. The candidate receipts will be included in the relay chain blocks.

The validators can verify the candidate receipts in a relay chain block based on certain information available to them. The collators and fishermen also assist them in the verification process. A detailed description of block production is outside the scope of this article.

Kusama: The canary network of Polkadot

Kusama is an early release of Polkadot created to test the network’s technology in a real-world environment. It also offers a place for parachain developers to test their ideas before deploying them to Polkadot.

Polkadot Launching process

Polkadot’s multi-stage launching process started in May 2020. The initial system had only limited functionalities which were gradually lifted through a series of upgrades and governance decisions. Polkadot has a complicated governance mechanism. The on-chain governance mechanism allows runtime upgrades without requiring any hard forks [3]. The logic is stored on the Polkadot blockchain itself, instead of nodes. So Polkadot can upgrade its runtime by upgrading the logic stored on-chain without interrupting the nodes.

The number of parachains in Polkadot is currently limited to 100. The parachain slots are assigned based on candle auctions. Each slot is leased for a maximum duration of 2 years. The winners of the first 6 auctions are AcalaMoonbeamAstarParallel FinanceClover and Efinity. The second batch of auctions is in progress.

Polkadot offers an excellent solution for interoperability among blockchains. Parachains can lease the security of the Polkadot network. The multichain network improves scalability by allowing parallel processing of transactions. Forkless upgrades offered by the on-chain governance mechanism create a comfortable execution environment for the nodes.


[1] Polkadot Wiki.

[2] Polkadot Lightpaper.

[3] https://wiki.polkadot.network/docs/learn-runtime-upgrades

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