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This FAQ focuses on technical questions for users interested in developing applications forPolkadot. If you have a more general question, you may wish to search for the answer on our supportKnowledge Base or the mainPolkadot network FAQ. If you have a question that is not answered,please feel free to ask on the Polkadot WatercoolerElement channel or contactPolkadot Support.
Polkadot Launch
The Genesis block of the Polkadot network was launched on May 26, 2020 at 15:36:21 UTC, as a Proofof Authority (PoA) network, with governance controlled by the single Sudo (super-user) account.During this time, validators started joining the network and signaling their intention toparticipate in consensus.
The network evolved to become a Proof of Stake (PoS) network on June 18, 2020. With the chainsecured by the decentralized community of validators, the Sudo module was removed on July 20, 2020,transitioning the governance of the chain into the hands of the token (DOT) holders. This is thepoint where Polkadot became decentralized.
The final step of the transition to full-functioning Polkadot was the enabling of transferfunctionality, which occurred on Polkadot at block number 1_205_128 on August 18, 2020, at 16:39UTC.
On August 21, 2020, Redenomination of DOT occurred. From this date, one DOT (old) equals 100 newDOT.
Polkadot Roadmap
For more information on the Polkadot roadmap please visit theofficial Polkadot website.
Consensus
Why do we need Consensus?
Consensus is a method for coming to agreement over a shared state. In order for the state of theblockchain to continue to build and move forward, all nodes in the network must agree and come toconsensus. It is the way that the nodes in a decentralized network are able to stay synced with eachother. Without consensus for the decentralized network of nodes in a blockchain, there is no way toensure that the state one node believes is true will be shared by the other nodes. Consensus aims toprovide the objective view of the state amid participants who each have their own subjectiveviews of the network. It is the process by which these nodes communicate and come to agreement, andare able to build new blocks.
What are PoW and PoS?
Proof of Work (PoW) and Proof of Stake (PoS) have been inaccurately used as short hand to refer toconsensus mechanisms of blockchains, but that does not capture the full picture. PoW is the methodfor agreeing on a block author and part of the fullerNakamoto consensus that also encompasses a chainselection algorithm (longest chain rule in Bitcoin). Similarly, PoS is a set of rules for selectingthe validator set and does not specify a chain selection rule or how a chain might reach finality.PoS algorithms have traditionally been paired with an algorithm for coming to Byzantine agreementbetween nodes. For example, Tendermint is a practicalByzantine fault tolerant algorithm that uses PoS as its validator set selection method.
Why not Proof of Work?
Although simple and effective in coming to a decentralized consensus on the next block producer,proof of work with Nakamoto consensus consumes an incredible amount of energy, has no economic orprovable finality, and has no effective strategy in resisting cartels.
Validators
How do I apply to be a validator?
There is no central authority that decides on validators, so there is not per se an applicationthat you can fill out. Registering as a validator is permissionless; in order to become one you mustonly set up a validator node and mark your intention to validate on chain. For detailed instructionon how to do validate you can consult thePolkadot validator guide.
However, once you've set up a validator and have registered your intention it does not mean that youwill be included in the active set right away. The validators are elected to the active set basedon the results of an election algorithm known as Phragmén's method.Phragmén's method tries to accomplish two goals: 1) select n members from a larger set based onstake-weighted votes and 2) equalize the stake backing each validator as much as possible.
You will likely want to campaign your validator to the community in order to get more backing. Youare looking for nominators that will put up their tokens to increase the stake for your validator.For validators who cannot acquire the minimum stake from the community, Parity and Web3 Foundationalso run a joint programme called Thousand Validators that will nominatevalidators if they apply and fit the requirements.
How are validators rewarded?
Validators are rewarded from the inflation of the Relay Chain,transaction fees, and tips. However, they onlytake a percentage of the former two. More details can be read on the page forvalidator payouts.
What is the minimum stake necessary to be elected as an active validator?
The minimum stake that is necessary to be elected as an active validator is dynamic and can changeover time. It depends not only on how much stake is being put behind each validator, but also thesize of the active set and how many validators are waiting in the pool.
There are a few ways to estimate the minimum stake.
One way can be to navigate to thePolkadot Apps Targets tab.The value at the top of the screen saying "Lowest" is the least staked validator. You need at leastthis much + 1 to enter the set.
You can also use some tools some to perform estimations.
Offline Electioncan provide exact results of running an election on the current set of validators using the sameRust code that is ran in Polkadot.
Validator stats script can give you an estimate that isbased on the currently elected set, as well as some statistics about Kusama validators.
Why Polkadot targets 1000 validators while other projects have hundreds of thousands?
Polkadot's goal to have 1000 validators is set to be something that is practically achievable in theshort term with high confidence of good performance in a live environment. Furthermore, validatorsin Polkadot are not the only stakers, and if we consider the number of stakers that can be possibleon Polkadot the number can scale up to hundreds of thousands. Since validators are performingcritical consensus work to maintain the security of the chain including all of its shards, a moremodest number of validators is estimated to start. Upon later improvements, such as implementingsignature aggregation for finalization messages, the number of validators could reasonably scale up.However, increasing validators above one thousand remains a goal for later iterations of Polkadot.
It is also worth mentioning that one thousand validators is more than the number of validators ofsimilar PoS chains with comparable levels of economic security as Polkadot. The closest contendersare operating with around 150 validators.
Additionally, other projects sometimes have a different definition of validator that approximatesmore closely to remote signing keys without the full operation of a validating node. On Polkadot,each validator is running their own validating node and performing full verification of the RelayChain, voting on finality, producing blocks in their decided slots, and verifying parachain statetransitions. Other projects may consider validators and "validating nodes" as separate entities.
Finally, individuals may participate in the block production process indirectly bynominating validators. In this way, individuals who are not running anode can still share in staking rewards.
Relay Chain
What is the block time of the Relay Chain?
Both the Kusama and Polkadot networks are currently operating at a rate of one block every sixseconds.
This may be changed in the future. It may go as low as two to three seconds after optimizations, orpotentially increase in order to handle the capacity of the parachain networking in a liveenvironment.
Does Polkadot have smart contracts?
No - and yes. The Polkadot Relay Chain does not implement smart contracts natively. The reason fornot having smart contracts on the Relay Chain is part of the design philosophy for Polkadot thatdictates that the Relay Chain should be the minimal logic required to accomplish its job.
While the Polkadot Relay Chain does not implement smart contracts directly, there are numerousparachains that do. It's possible for parachains to enable smart contract functionality and thenbenefit from the security and interoperability features of Polkadot. Additionally, existing smartcontract chains can connect to Polkadot as a parachain, or via a bridge.
So it's better to say that the Polkadot ecosystem has smart contracts versus "Polkadot has smartcontracts."
How does the Polkadot Relay Chain connect to external chains in the ecosystem?
One of the cornerstone interoperability technologies being researched and developed for deploymenton Polkadot is cross-chain bridges. Bridges come in a variety offlavors with varying levels of trust associated with them. Polkadot is predominantly researching thetrust-minimized flavor that imposes economic costs on the operators of the bridge, and thereforemakes it economically secure. Bridge efforts are being worked on in concert with other projects inthe ecosystem.
What is Polkadot's Transactions Per Second (TPS)?
Polkadot is a heterogeneous sharded network comprising a relay chain and numerous parachains, whichare all individual blockchains built on Substrate executing in parallel.Hence, the Transactions Per Second (TPS) of Polkadot is a number that encompasses all thetransactions on the relay chain as well as parachains. As the transactions on these Substrate-basedblockchains are weights based, it makes sense touse TPS as a measure for the network performance if all the transactions carry the same weight.Performance benchmark tests show thatSubstrate-based blockchains can achieve over 1000 TPS for balance transfer transactions. AssumingPolkadot is running over 100 parachains; the projected TPS is well over 100,000. Withasynchronous backing upgrade, the TPS is expected to increasetenfold to 1,000,000.
It is essential to realize that TPS is inherently a subjective measurement with numerous factorsthat can contribute to it. It's hard to gauge the usefulness of TPS in isolation (when compared toother chains), as it depends on what a transaction does for a particular network. To view howPolkadot measures TPS see the Polkadot sTPS(Standard Transaction Per Second)to consider precisely how benchmarking was performed for Polkadot.
DOT
What is the difference between DOT (old) and new DOT?
The DOT (old) unit on Polkadot was at twelve decimal places, otherwise known as 1e12 Plancks. On 21August, 2020, Denomination Day, the DOT (old) value was redenominated to 1e10 (10_000_000_000, orten billion) Plancks, meaning that the new DOT was valued at ten decimal places. Following theredenomination, the new DOT is called DOT.
What is the inflation rate of the DOT?
The inflation rate is approximately 10% per year.
A portion of the inflation is rewarded to validators for performing their duties, while anotherportion may go directly to the treasury. The exact percentage that goes into both varies and isbased on the amount of DOT that are staked. Please see the article oninflation for more information.
Why can't crowdloaned DOT be staked?
DOTs contributed to a successful crowdloan campaign by a parachain are bonded for the entire leaseperiod, which is two years on Polkadot. The crowdloaned DOT cannot be used for any other DOT utilityfunctionalities like staking and democracy. In exchange to the lost staking rewards or liquidity ofDOTs, the parachain team may offer rewards to the contributor.
The utility of crowdloaned DOT is to provide a lease for a parachain. The utility of staked DOT isto secure the network through a reward/slash mechanism. Allowingcrowdloaned DOT to be staked results in complex consequences like applying a slash on crowdloanedDOT that was meant to be bonded for the entire lease period of a parachain. In a way, theinaccessibility of crowdloaned DOTs and the lack of staking rewards for the entire lease durationencourages the contributors to back projects that are valuable to the ecosystem.
Governance
What prevents Polkadot governance from failing?
Polkadot's governance has already been shown to work. Examples can be found in the runtime upgradesthat have successfully taken place through on the testnets as well as in a real economic environmenton Kusama and Polkadot itself.
It is fair to say that the field of on-chain blockchain governance is still new, and no one canclaim to know exactly what the optimal version of on-chain governance is yet. However, Polkadottakes a brave step forward in pioneering thought-through mechanisms for evolving a blockchain.
Blockchains need a method to adapt and evolve. Therefore, an on-chain governance system wasnecessary for the long-term success of Polkadot. Ultimately, it is the token holders that areresponsible for preventing Polkadot's governance from failing by using their economic value andconviction to sway the progression of the protocol.
What prevents Polkadot governance from becoming plutocratic?
A savvy reader might have noticed that the answer to the previous question endowed the token holderwith the ultimate responsibility to ensure that Polkadot's governance does not fail. By followingthe train of this assertion, one might assume that Polkadot's governance is susceptible to becomingruled by a few large token holders (called whales in trading parlance) and therefore become a mereplutocracy (rule of the rich).
There are several other mechanisms that are built-in to the governance system to resist thisplutocratic tendency. One of these mechanisms is called conviction voting, and imbues greater votingpower to token holders who are willing to lock their tokens on the protocol for longer lengths oftime. Longer lock-ups display conviction in a vote. Conviction voting could allow a highlydetermined minority to overrule the vote of an apathetic majority in certain situations. Anothermechanism is known as Adaptive Quorum Biasing. This makes proposals have a varying threshold forapproval or rejection based on what part of the governance protocol the proposal originated in. Fordetails on the subtleties of Polkadot's governance system, please see thegovernance page.
Parachains
How do parachain economics work?
Parachains have the flexibility to implement their own monetary system or incentive structure forcollators. However, this is not strictly necessary. Since the collator's job is to continue to giverecent state transitions to the validators on the Relay Chain who validate each transition, thesecurity of the parachain and the Polkadot network is completely separate from parachain economics.Parachains need collators to continue to progress, so it wouldn't be unreasonable to see themincentivize collator nodes in some way, but the specific mechanism is completely up to parachainimplementers.
Are parachains ephemeral? What happens when a parachain loses the next auction?
Parachains are not ephemeral. As long as someone is keeping the data for a parachain, the parachaincan move between being a parachain, anon-demand parachain, or a separate sovereignchain at different points of its lifetime. Especially with on-demand parachains, parachains canproduce blocks when their usage and throughput makes it necessary.
When a parachain loses an auction for renewal, that parachain has a few options. In most cases,becoming an on-demand parachain instead would be a suitable choice. On-demand parachains are stillsecured by the Relay Chain, but don't need to hold a parachain slot and can produce a block when itseconomically feasible for them. For more on parachains please see theparachains page.
Networking
What is libp2p?
Libp2p is a modular and extensible networking stack that is used by IPFS,Substrate, and many other projects. It is a collection of peer-to-peer protocols for finding peersand connecting to them. Its modules have logic for content routing, peer routing, peer discovery,different transports, and NAT traversals. It is intended to be used by applications for buildinglarge scale peer-to-peer networks by only selecting the parts of the protocol suite that are needed.
The Rust implementation of the specification was built and primarily maintained by a team ofcontributors at Parity Technologies. The Go and JavaScript versions are maintained by Protocol Labsas well as community contributors. A Nim version of thelibrary also exists. Libp2p as a whole is an open source project that is actively developed andexpanded on various code repositories hosted on their GitHub.
Does Polkadot use libp2p?
Yes, since Polkadot is built with Substrate. Substrate uses a networking protocol that is based onlibp2p (specifically the Rust libp2p library). However, Substrate uses a mix of standard libp2pprotocols and protocols that are homegrown and not official libp2p standards. Of the standardsprotocols, those which are shared with other implementations of libp2p such as IPFS, areconnection-checking (ping), asking for information on a peer (identity), and Kademlia random walks(kad).
Of the protocols that are custom to Substrate, there are the legacy Substrate stream, arequest-response for getting information on blocks (sync), a light client protocol, a notificationprotocol for transactions, and block announcement. For detailed information on how Substrate useslibp2p and the standard and custom protocols, please see thenetworking documentation.
How does libp2p differ from IPFS?
The Interplanetary File System (IPFS) is a peer-to-peer hypermedia protocolused primarily for storage of files. It allows one to upload a file onto the network and share itwith its content addressable URI. IPFS, like Substrate, is an application of libp2p and existshigher on the technology stack. Although both IPFS and Substrate use libp2p, it cannot be said thatSubstrate "uses" IPFS since besides sharing the underlying library for networking there is no nativeintegration between the two applications.
Kusama
What is the minimum amount of KSM / DOT I can have in my account?
Please see information about Existential Deposits.
What are the transfer fees for Kusama?
It is important to note that the cost of transferring KSM is dynamic. Currently, the minimum cost oftransferring KSM is 0.01 KSM (the base fee), although this can be changed via governance. However,actual transaction fees vary based on a variety of factors. Specifically, fee calculation followsthe following formula:
base_fee + (tx_length * length_fee) + WeightToFee(weight)
Please see thefee calculation page inthe Substrate documentation for more detailed information.
Answered by Gav series
The "Answered by Gav" series is a collection of posts uploaded to Reddit of questions that have beenasked in the Polkadot Watercooler Riot channel and answered by Polkadot founder Gavin Wood.
- Reason for using asynchronous rather than synchronous communication? Difference in terms of TPS?
- How exactly do validators in an ETH parachain keep moving around and how is communication between zones trustless?
- What are the main issues with Bitcoin integration and will it ever be possible? Same problem with other POW chains? Is Polkadot only going to work with POS chains? How is it trust-less in comparison to Cosmos though?
- What are the current thoughts around governance especially since projects have to be voted in to receive the parachains security?
- Also is there any detailed overview of how exactly a token transfer from ETH could be exchanged with another chain's currency?
- Can I run multiple Validators with the same Session Key?
- How to tackle the concentration risk of Validators in data centers?
