"What is Polkadot?" A popular science article about Polkadot that everyone can understand

The author of this article is Bruno Škvorc, a developer and blockchain science popularizer from Croatia.

In 2015, Bruno joined the Ethereum ecosystem full-time and created popular science tutorials and programming courses for many novice developers, and also followed various news events. Since 2018, Bruno has begun to assist an ETH2.0 team in development; after 2019, Bruno became a professional technical science worker at the Web3 Foundation, dedicated to promoting the Web3 vision to ensure that anyone, anywhere can access a trusted Internet.

By Bruno Škvorc

Bruno cares deeply about decentralization, anti-censorship, transparency, and accountability, so he is passionate about immutable ledgers. He holds a master's degree in computer science and English language and literature, and is interested in getting involved in virtual reality when conditions allow.

The following article is a high-level summary of Polkadot by Bruno after he assisted the Web3 Foundation for nearly three years and wrote a large number of popular science articles on Polkadot. The writing style of this article continues Bruno's usual style, which is to be as professional as possible to ensure that everyone can understand it.

What is Polkadot? How is it different from existing blockchains? What is the significance of Polkadot? Which public chains compete with Polkadot? This article will explain these questions in a very high-level way, so that beginners who are only familiar with the most basic blockchain terms but do not have any professional technical knowledge can also fully understand them.

1. Polkadot’s operating mechanism

Polkadot has a main chain created based on Substrate, called the Relay Chain, and other blockchains linked to this main chain are called parachains.

There are many types of parallel chains linked to the relay chain, which can be Bitcoin/Ethereum/Tezos/Edgeware. They can generate blocks in any self-consistent way. For example, Bitcoin can generate blocks according to its own specifications, Ethereum can generate blocks according to its own specifications, Tezos can generate blocks according to its own specifications, and the smart contract blockchain Edgeware can also generate blocks according to its own rules.

Relay chain, parachain, bridge

The parachain obtains finality from the relay chain - this is a property of finalizing the block (transactions on it) to ensure that the transactions that have occurred cannot be "undone".

Author's note: Once a blockchain forks, the original transactions on the block may be restored (for example, A transfers 10 BTC to B, and this BTC has been packaged and confirmed. Once the blockchain forks, these 10 BTC may return to A's account again. Therefore, it is very important to prevent transactions from being restored on the blockchain. On the Polkadot network, the relay chain gives parallel chains such capabilities). A fork is a disagreement between different software versions of the same blockchain, where one set of programs (or nodes) builds blocks in one direction, and another set of programs builds blocks in another direction.

Forks are very common on the blockchain. Normally, forked chains will die out on their own, but in extreme cases, the length of the fork may exceed the original chain until it replaces the original chain and becomes the main chain. In this case, transactions on the forked chain will replace transactions on the original chain.

The emergence of Polkadot is not to compete with any mainstream public chain in the existing blockchain world, including ETH2.0. On the contrary, Polkadot hopes to "hold up" all chains in order to achieve cross-chain communication between different blockchains - the goal is to build a unified ecosystem for the decentralized blockchain world.

2. Cross-chain composability

We know that Bitcoin is an independent blockchain, and Ethereum is an independent blockchain. The two are different and operate independently. The two blockchains are like two closed walled gardens. They confine their "exquisiteness" to two small spaces. The value locked in Bitcoin cannot enter Ethereum, because you cannot transfer your Bitcoin to others in the absence of centralized trust.

Author's note: Some people may ask, why do I have to transfer BTC to Ethereum? This is because Ethereum's supporting DeFi is a very prosperous ecosystem. Anyone can issue assets, get loans, or synthesize BTC into other assets to circulate their assets. On the Bitcoin network, you can't do anything but watch your assets sit there.

“Polkadot is a cross-chain communication system.”

On Polkadot, different blockchains can communicate with each other in a decentralized manner, allowing developers to develop cross-chain applications and allowing one parallel chain to send messages to another parallel chain. You can let your imagination run wild. The messages here can be financial assets, chat information, atmospheric monitoring data, etc., and of course it can also be 10 bitcoins sent by an investor from Bitcoin to Etherum.

Author’s Note: For a more professional explanation of Polkadot’s cross-chain technology, the author has specially produced a video to explain it. Please click on the “original link” to view it.

3. Shared security

The relay chain is essentially a blockchain. Validators safeguard the security of this blockchain. Validators run Polkadot nodes. Validators are occasionally given the power to generate new blocks. If they perform their duties diligently and well, they will be rewarded.

Validators, collectors, nominators and fishermen on Polkadot. This article only covers validators on the relay chain.

Anyone can become a validator as long as they have enough chips behind them. The so-called chips here are DOT, the "national currency" of the Polkadot relay chain. According to the number of DOT staked, the first few hundred validators will be elected as active validators in turn.

Author’s note: If validators do a terrible job, they will be punished, for example, if their nodes are offline when the network needs them to work, then their staked DOTs will be reclaimed, effectively confiscated.

The elected active validators are randomly assigned to each parachain, and every few hours, this assignment will rotate again in a random and unpredictable manner.

Every 6 seconds, the parachain sends a candidate block to the relay chain. This candidate block will be verified by the validators on the relay chain who are online at that moment. If the verification is passed, the candidate block will be included in the relay chain's block, and then the parallel chain will generate the next candidate block. After the submission is completed, these blocks become immutable, and the parachain grows carefree under the protection of the relay chain.

All parachains ultimately need to obtain final authorization from validators on the relay chain. The more parachains there are, the more validators are needed, and the higher the security of the entire network. Important reminder: If you want to become a validator, you must stake DOT tokens. When you perform the role of a validator, your DOT will be staked in the Polkadot network.

In this way, the relay chain shares security with the parachains, and each chain becomes part of the overall network's resistance to attack.

4. Forkless Upgrades and Governance

Generally speaking, when a blockchain is upgraded, forks are inevitable: some nodes are upgraded, while others are not. The nodes that are not upgraded will always stay on the forked chain until the chains that are not upgraded are updated. The network upgrade is complete only after these nodes are updated. What is even more painful is that these nodes are distributed around the world, and you cannot communicate with these anonymous nodes in real time.

Polkadot solves this problem through "on-chain runtime and on-chain governance". On-chain runtime means that the code containing the rules for generating new blocks is stored on the chain. Therefore, the nodes and programs running the blockchain only need to read this information, and they can be updated. So how do we update this code?

On-chain governance allows any DOT holder to initiate or vote on a referendum. A referendum is a proposed change to the blockchain logic or data. Through governance, the community can propose and vote on changes to the on-chain logic, and once the logic change is voted through, it will be automatically updated without the need to update the software or require manual intervention.

Author’s Note: Detailed information on on-chain governance can be found on the Polkadot wiki .

If you would like to see more posts about Polkadot, or keep up with the progress of the Web3.0 Foundation, including news, development tools, or development progress, please submit your email address through the link at the end of the original article.