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Glossary


A


Account

Accounts allow you to keep separate records of your DCR funds. Transferring DCR across accounts will create a transaction on the blockchain.

Address

A human-readable representation of a possible destination for a payment, similar to an email address. Unlike an email address however, there are a variety of address types, and most addresses are intended only for a single use. This is because addresses represent not only the destination of a payment, but constraints required to redeem funds. For the most common type of address, the constraints require that the recipient provide both the public key which hashes to the requisite hash and a valid signature that is created from the corresponding private key. Other address types require signatures from multiple parties (multi-sig), signatures created within specified time limits, or other more complex constraints.

Atom

The smallest unit of Decred currency. One atom is one hundred millionth of a single DCR (0.00000001 DCR).

B


Block

The data structure transactions are bundled into before being written into the distributed ledger. Decred’s difficulty adjusts such that new blocks are found every five minutes on average.

Block explorer

A tool for inspecting the contents of blocks in a more user-friendly format.

Block header

Metadata at the beginning of a block that defines information about the block. The hash of a block header is the main way of identifying a block.

Block reward

A reward (in DCR) split between PoW miners, active and chosen voters, and the Treasury for successfully creating a block of transactions. The block reward decays exponentially with block height (length of blockchain). However, Decred’s algorithm interpolates this decay over time so as not to produce market shocks, as typically seen in algorithms that involve large and infrequent reductions, such as halving the rewards every 4 years. The block reward started at 31.19582664 and it adjusts every 6,144 blocks (approximately 21.33 days) by reducing by a factor of 100/101.

Block voting

In each block, five tickets are called to vote. In addition to votes on any open consensus rule change proposals, each ticket votes to approve or reject the regular transaction tree of the previous block. If a majority of voting tickets vote Yes, the regular transaction tree of the previous block is accepted. If a majority of voting tickets vote No (or there is a tie), the regular transaction tree of the previous block is rejected and those transactions are returned to the mempool.

C


Command Line Interface (CLI)

An interface a user interacts with via the command line - often referring to a CLI wallet, which is operated using various tools and commands.

Confirmation

A transaction is confirmed when it has been included in a block that has been verified by the network (added to the blockchain). Each additional block added to the blockchain reconfirms all transactions in all previous blocks. The number of times a transaction has been confirmed is used as a measure of confidence that the transaction will remain in the blockchain. A wallet or other service may require a certain number of confirmations before it considers a transaction to be valid. For example, if a wallet requires three confirmations to consider a transaction valid, it would require the next two blocks after the block including the transaction to confirm the transaction.

Consensus rules

Rules, encoded in software, that allow a network of nodes to reach an agreement about the state of the ledger. Rules include what data blocks can contain, how block data is structured, and how nodes validate blocks.

Consensus rules voting

Changes to Decred’s consensus rules can only be made through an on-chain voting process which lasts for around one month. The change is made only if at least 75% of votes are in favor.

Constitution

A document which defines the purpose and guiding principles of the Decred project.

Credits

The full unit of the Decred currency (i.e. 1 DCR).

D


DCR

Ticker for the Decred currency.

Decred Change Proposal (DCP)

A design document that describes potential protocol or consensus changes to Decred. DCPs primarily serve for documentation, fostering cross-implementation compatibility and helping ensure proper engineering rigor is followed.

Decrediton

A GUI (Graphical User Interface) Decred wallet maintained by the core team.

Difficulty

Difficulty is a measure of how difficult it is to mine a new block (i.e. find a hash below a given target). In Decred, the PoW difficulty is calculated from the exponentially weighted average of differences in previous block times.

Distributed ledger

A cryptographically secure ledger, composed of nodes in a network, where each node holds a copy of the same ledger.

E


Expired ticket

Tickets that reached the end of their window without being called to vote - these can be revoked, but do not grant a reward.

F


Faucet

A mechanism for obtaining free (testnet) coins.

H


Hash

The output of a cryptographic hashing function that produces a fixed-size value from variable-size input. While it is computationally easy to create a hash from an input, it is extremely computationally difficult to calculate an input that will produce a given hash.

Hash function

A cryptographic function that produces a fixed-size hash value from variable-size transaction input. Decred’s Proof-of-Work uses the BLAKE-256 hashing function.

Hashrate

The number of hashes per second computed by miners on the network.

Hybrid PoW/PoS

In Decred, a hybrid PoW/PoS system is used, whereby blocks mined by PoW miners must be approved by ticket holders, which are pseudorandomly selected from the ticket pool. This provides a check on PoW miners and increases the overall cost of attacking the network. When a block is approved, 60% of the block reward goes to the PoW miner, 30% goes to the holders of tickets called to vote (approve blocks), and 10% goes to the Decred Treasury to fund the project.

I


Immature ticket

Once tickets are mined they are immature for 256 blocks (about 20 hours) and cannot be called to vote until after this period elapses.

Inflation

Increase in the available supply of Decred as new DCR is minted into existence through the block reward.

L


Live ticket

Tickets that are waiting to be called.

M


Mainnet

The proper Decred network - a term used to differentiate from testnet.

Mempool

Transactions waiting to be mined.

Miners

Miners help secure the network via Proof-of-Work (PoW) mining. Miners recieve block rewards and transaction fees for successfully validating blocks.

Mining Pool

A group of miners who share (pool) their computational resources to mine DCR. When a member of a mining pool successfully mines a block, the rewards are typically split among all pool members in proportion to the hashpower they contribute to the pool.

Missed ticket

Tickets that have been called but did not receive a reward. This can happen if a ticket is called to vote, but the wallet that bought the ticket does not respond. This can also happen if the wallet does respond and broadcasts its vote to the network, but a miner does not include their vote in the following block.

O


Orphan block

Orphaned blocks are valid blocks which are not included in the definitive blockchain. Orphan blocks can occur when they are part of a branch of the blockchain that has been abandoned. This can occur naturally when two miners produce blocks at similar times. Orphan blocks can also be created when they build on an unknown block (i.e. the “parent” block is unknown, making it an “orphan”).

Orphan transaction

A transaction with missing inputs (i.e. the “parent” transaction is unknown, making the transaction an “orphan”). Orphan transactions can also be created when they are part of a block that has been abandoned and have not been included in another block. For example, if a miner creates a valid block with transactions specific to them, such as coinbase transactions and votes, and that block is orphaned, the transactions in that block will become orphaned transactions.

P


Politeia

A system for facilitating the submission and discussion of proposals in an environment with transparent censorship.

Private key

An astronomically large number which, when kept secret from others, enables legitimate spending of personal Decred while preventing others from spending it. Private keys are encrypted by wallets to prevent theft.

Private passphrase

A passphrase that is used to encrypt parts of the wallet.db file; most notably private keys. The private keys can not be accessed unless the passphrase is used to decrypt them.

Proof-of-Stake (PoS) voting

The mechanism by which ticket holders vote to approve blocks confirmed by PoW miners (thus providing a check on PoW miners), earn staking rewards, and vote on consensus rule changes and Politeia proposals.

Protocol rules

See consensus rules.

Public key

An astronomically large number generated algorithmically from a private key. Public keys can be freely shared without revealing any information about the private key they are generated from. The user’s public key is used to prove that a transaction was signed using their private key.

Q


Quorum

The minimum level of participation required in order for a decision-making process to produce an actionable outcome. Changes to the consensus rules require at least 10% of votes to be for or against the change in order to be valid. Politeia proposals require 20%.

R


Regular transaction tree

The normal transactions in a block: sending DCR to an address, coinbase transactions such as PoW Miner reward and Treasury stipend.

Reorg

A reorganization (or reorg) of the blockchain is when a set of blocks are replaced by another set which has more work. The number of blocks replaced is the depth of the reorg.

Revoked ticket

When a ticket (that was missed or expired) is revoked, the DCR used to buy it becomes spendable again.

Rule Change Interval (RCI)

An interval of 8064 blocks (~4 weeks) in which ticket holders can vote on consensus rule changes. A Rule Change Interval (RCI) consists of four Stake Version Intervals (SVI), which are 2016 blocks (~1 week). Once the conditions for a vote have been met during an SVI, voting is scheduled to begin on the first block of the next RCI. Because there are four SVIs per RCI, it can take up to 6048 blocks [3 SVIs] for the next RCI to begin.

Rule change proposal

A proposal to change the consensus rules of the Decred blockchain. Rule change proposals must be implemented in latent code within the software running the network’s nodes. If the proposal passes, the latent code activates one month later.

S


Seed

A 256-bit (32-byte) cryptographically secure random number that can be used to recover a wallet. When creating a wallet using any Decred wallet software, a 33 word “seed phrase” is also created from the 32-byte seed. If the wallet is lost or corrupted, the seed phrase can be used to restore the wallet’s private keys, transaction history, and balances using any Decred wallet on any computer.

Simnet

A simulation network with very low difficulty, such that a developer can mine new blocks locally at will for testing purposes.

Simple Payment Verification (SPV)

A wallet mode in which only blocks related to addresses owned by the wallet are downloaded. When not in SPV mode, wallets must download all blocks in the blockchain to verify transactions (fully validating mode). SPV mode allows wallets to operate with less stringent hardware requirements and load significantly faster. SPV wallets cannot vote, but can purchase tickets and allocate voting rights to a Voting Service Provider (VSP).

Stake transaction tree

Transactions relating to ticket buying and ticket voting rewards.

Stake Version Interval (SVI)

An interval of 2016 blocks (~1 week) which is used to determine if a vote on concensus rules can begin. Before a vote on consensus rule changes can begin, 75% of tickets that vote during a Stake Version Interval (SVI) must be using software that contains the latent software change being proposed.

Stakepool

See Voting Service Provider.

Staking

Colloquial term for time-locking DCR in exchange for tickets.

T


Testnet

A parallel network used for testing, where DCR can be obtained freely from faucets.

Ticket

Decred holders can time-lock DCR in exchange for tickets. Tickets grant their holder the ability to vote, and it is through ticket voting that major governance decisions are made. The DCR locked to buy a ticket is unlocked after that ticket is called to vote on-chain (this averages around one month, maximum around 4 months), along with a reward. Around 0.5% of tickets are not called before they expire; in this case the DCR is un-locked but no reward is granted.

Ticket pool

The pool of live tickets that are available to be called to vote. The target size for the ticket pool is 40,960.

Ticket price

The amount of DCR one must time-lock in order to buy a ticket. The ticket price is algorithmically adjusted with the goal of keeping the ticket pool at an optimal size of 40,960 tickets. The algorithm for setting the ticket price was changed by DCP-0001, the first consensus rules change to be adopted using an on-chain vote.

Ticket-splitting

The process of buying part of a ticket. This is done by coordinating with other parties who will buy the other parts of a ticket. This can be done without giving up custody to your DCR. The minimum amount of DCR that can be put into a split ticket is 5 DCR. Ticket-splitting is currently coordinated through the ‘ticket-splitting’ channel on the Decred slack channel.

Transaction fees

A fee paid to have your transaction included in a block. The default transaction fee for Decred is 0.0001 DCR/kB.

Treasury

The Decred Treasury holds funds for use in development of the project. Decisions about how to use these funds are made through Politeia proposals and voting.

U


Unmined ticket

Immediately after a ticket is bought it is unmined until the transaction is included in a block.

V


Voted ticket

Tickets that have been called and responded with votes; once a ticket has voted, the DCR locked to buy it becomes spendable after 256 blocks.

Voters

People who buy tickets and vote with them.

Voting Service Provider

Non-custodial services that can be authorized to vote on behalf of a ticket, usually providing a number of geographically distributed servers to reduce the chance of missed tickets.

W


Wallet

A file that stores private keys. Wallets allow their owner to view and create transactions on the blockchain. The Decred team maintains a GUI wallet (Decrediton) and Command Line Interface (CLI) wallet tools for advanced users. Decred is also supported by numerous 3rd party wallets.

Watch-only

An address or pubkey script stored in the wallet without the corresponding private key, allowing the wallet to watch for outputs but not spend them.