This glossary contains terms that are actively implemented and used within the QF Network ecosystem. These terms represent the core components, technologies, and concepts that make up the current QF Network implementation.
Accelerator
A designated special player responsible for fast transaction confirmations during optimistic scenarios.
Anchor Chain
High-value PoS network (like Polkadot) that validates and finalizes Fast Chain proofs to provide additional security guarantees.
Archive node
A node that stores a complete record of states for every block and the entire blockchain history.
Authority-based round-robin scheduling (AURA)
Provides a slot-based block authoring mechanism, where a known set of authorities take turns producing blocks.
B_heartbeat_interval
Number of blocks between leader liveness heartbeats sent to parachain
B_recovery_delay
Number of parachain blocks after the last FCFP before the parachain initiates Finality Recovery Mode.
B_recovery_duration
Number of parachain blocks that Finality Recovery Mode continues before transitioning back to operational mode.
BLAKE3
High-performance cryptographic hash function used as universal hashing primitive in QF Network
Blind Assignment for Blockchain Extension (BABE)
Polkadot's block production mechanism
Blob
Binary data stored on the blockchain, particularly in smart contract context.
Block
A collection of data, such as transactions, that together indicate a state transition of the blockchain.
Block Batch
Set of Fast Chain finalized blocks submitted to Anchor Chain in one transaction through the Bridging Gadget.
Block Explorer
A web tool for inspecting and navigating detailed blockchain data, including blocks, transactions, addresses, and smart contracts.
Block Viewer
A simplified interface specifically for viewing basic block data and recent transactions without the additional analysis features of a full explorer.
Blockchain
A distributed ledger technology that maintains a continuously growing list of records (blocks) secured using cryptography.
Blockchain Trilemma
A well-known problem in blockchain design asserting that a decentralized system can only achieve two out of three properties: decentralization, security, and scalability. SPIN's hybrid consensus aims to mitigate this by allowing fast, scalable networks to inherit security from larger, established chains
Bootnode
Initial node that helps others connect to the network.
Bridging Gadget
Finite State Machine executed on Anchor Chain that validates Fast Chain Finality Proofs and manages recovery procedures.
Bridging Gadget Operators
Validators responsible for operating the Bridging Gadget, submitting FCFPs to the Anchor Chain, and managing cross-chain communication.
Bulk Coretime
A purchasing model for parachain slots on Polkadot using bulk time allocation.
Cap'n Proto
High-performance RPC serialization protocol with zero-copy decoding and promise pipelining
Chain Growth
Chain Quality
Minimum portion of blocks from honest nodes.
Chopsticks
A mechanism for creating a test environment on Polkadot SDK (ex Substrate) (similar to a sandbox) for sending transactions via RPC
Collator
Type of node (typically near full node) in the parachain Polkadot SDK-based (ex Substrate) network. Responsible for validating, block production, pre-finalization of blocks and communication with relay chain (for example with validators).
Committee
A predefined subset of nodes tasked with verifying transactions rapidly in cooperation with the Leader
Common Prefix
A consistency property: the chain of an honest node is a prefix of any other honest node's chain.
Consensus
The process by which network participants agree on the state of the blockchain
Consistency, Availability, and Partition Tolerance (CAP theorem)
Theorem states that a distributed data store can only provide two out of the following three guarantees simultaneously: Consistency, Availability, and Partition Tolerance.
contracts-ui
Web interface for deploying and interacting with smart contracts
Coretime
Dashboard
Visual overview of network performance, blocks, and usage.
decentralized Application (dApp)
Application that interacts with a blockchain using RPC to read data and a wallet to write to the blockchain.
DevNet
A development network environment for early testing of blockchain functionality before TestNet deployment.
EcoSystem
The complete environment of interconnected applications, services, and components that make up the blockchain network.
Election Finalization Block
Specific block where validator election results are determined and finalized, occurring after the Last Voting Block.
Epoch
A block production period with pre-known starting time and fixed-length during which the set of block producers stays constant. Epochs are indexed sequentially and divided into equal-length periods known as block production slots. Each slot is awarded to a subset of block producers during which they are allowed to generate a block. Governance, nomination, and validator selection processes occur within epoch boundaries to determine the validator set for subsequent epochs.
Extrinsic
Extrinsics are transactions that originate outside of the blockchain runtime. They are calls to functions within functional pallets on the blockchain and can be executed successfully, provided the caller has the necessary permissions.
Fast Chain
QF Network's main blockchain with 100ms target block time that processes normal transactions and maintains sovereignty while anchoring to Polkadot.
Fast Chain Finality Proof (FCFP)
Cryptographic proof consisting of block hash signed by majority of Fast Chain Validators, submitted to Anchor Chain for validation.
Fast Chain Nominations Proof (FCNP)
Cryptographic proof containing sufficient data for verifying Fast Chain nominations changes.
Fast Chain Validator Set Proof (FCVSP)
Cryptographic proof containing sufficient data for verifying Fast Chain validator set changes.
Fast Path
An optimistic execution path where transactions are instantly confirmed through the cooperation of the Leader (accelerator) and Committee without waiting for standard blockchain delays.
Faucet
A service that distributes test tokens to users on DevNet or TestNet
FCFP Block
A block whose hash and finality justifications are included in a Fast Chain Finality Proof.
FCFP Tail
Sequence of blocks covered by a single FCFP, from the FCFP Block back to the previous FCFP Block.
FCFP Transaction
Transaction submitted to Bridging Gadget containing FCFP along with block batch headers.
Finality Recovery Mode
Emergency procedure activated when Fast Chain finality stalls, using Anchor Chain to restore consensus and elect new Primary Leader.
Finalized Block
A block that has been accepted as canonical and will not be reverted.
Forkless Runtime Upgrades
A mechanism to update blockchain logic without requiring hard forks.
Framework for Runtime Aggregation of Modularized Entities (FRAME)
Full node
A node that stores the entire blockchain history and current state, validates transactions and blocks.
Gas
A fee or cost required to conduct a transaction on the blockchain, denominated in small fractions of cryptocurrency
Gas limit
The maximum price a cryptocurrency user is willing to pay when sending a transaction, or performing a smart contract function.
Gas Metering
System for measuring and limiting computational resources used by transactions or smart contracts.
Genesis Block
The first block of the blockchain from which all subsequent blocks build.
GHOST-based Recursive Ancestor Deriving Prefix Agreement (GRANDPA)
A finality gadget for blockchain consensus.
Gossip Protocol
Graceful Degradation
Ensures system performance transitions smoothly from an optimal fast path to a slower consensus mechanism without failure.
HashDB
An interface for accessing blockchain state similar to a key-value store.
History
Chronological sequence of confirmed blocks and finalized states.
Inclusion Proof
Cryptographic proof showing that a specific transaction was included in a finalized Fast Chain block.
Instant Confirmation
The capability to confirm transactions almost immediately (within network delay bounds) under optimistic conditions.
iroh
Key Management
Tools and practices for managing cryptographic keys.
Last Voting Block
Designated block after which no more validator candidate intentions or nominator votes can be submitted during an epoch.
Layer 1 (L1)
The base layer of blockchain architecture that includes data storage, transaction processing, consensus, and RPC.
libp2p
A modular network framework used in blockchain systems for peer-to-peer networking.
Light Client
A blockchain client that stores minimal data and relies on full nodes for verification.
Light node
A node that stores only part of the blockchain state and verifies data using full nodes.
Log-Structured Merge Tree (LSM tree)
Data structure that is optimized for write-heavy workloads.
MainNet
The production blockchain network where real-value transactions occur.
Merkle Proof
Cryptographic verification mechanism that allows light nodes to verify data without storing the entire blockchain.
Merkle Tree
A tree data structure where every leaf node is labeled with the cryptographic hash of a data block, and every non-leaf node is labeled with the hash of its child nodes.
Metadata
Data that includes information about other data, such as information about a specific transaction.
Metric(s)
Quantifiable measurements used to track and assess the status of specific processes in the blockchain.
Mode Switch Proof
Fast Chain transaction proving recent mode change (recovery/operational) in the parachain, containing mode value and parachain finality proof.
N_slashing
Percentage of stake slashed for proven censorship or malicious behavior by validators.
N_validators_max
Maximum number of validators allowed in the active set
N_validators_min
Minimum number of validators required for secure network operation.
N_validators_quorum
Percentage of validators required to validate and finalize blocks.
Node (as blockchain node)
A machine running the blockchain engine, which can store blocks and participate in the network.
Node (as network node)
A node that participates in network exchange, for example, a seed server
NOISE
Cryptographic protocol framework for secure key exchange without centralized certificate authorities
Nominated Proof of Stake (NPoS)
A consensus mechanism where network participants (nominators) delegate their stake to trusted validator nodes.
Normal Transactions
All blockchain transactions excluding operational transactions - regular user and smart contract transactions.
nQUIC
A modified version of the QUIC protocol using the NOISE protocol for key exchange.
Operational Transactions
Blockchain transactions required for maintaining network operation, such as consensus messages and validator updates.
Optimistic Conditions
Conditions where the leader is honest and available, and a large fraction of nodes are correct, enabling fast-path confirmation.
Optimistic Responsiveness
Confirms transactions as fast as the actual message delay in the network, assuming a supermajority of honest players and an honest accelerator.
Orphaned Block
A block that has not reached finalization.
Pallet
Modular component in Polkadot SDK (ex Substrate) that implements specific blockchain functionality.
Parachain
A specialized blockchain that runs in parallel to Polkadot's Relay Chain, sharing its security and interoperability features
Pessimistic Conditions
Conditions under which optimistic assumptions fail, causing the protocol to fall back to slower consensus.
PolkaVM
A smart contract execution environment based on the RISC-V instruction set.
Portal
A comprehensive web interface for interacting with a blockchain network that combines multiple tools including block exploration, wallet connectivity, network statistics, and developer tools.
Precompile
Built-in functions in blockchain runtime that execute at near-native speed.
Primary Leader
Designated Fast Chain validator responsible for producing blocks with normal transactions during assigned tenure.
ProofStorage
A mechanism for generating Merkle proofs from blockchain state.
Pruning Node
A node that discards older blocks to save storage space while maintaining current state.
QMDB
An embedded key-value store designed specifically for storing Merkelized data in the blockchain context.
R_bridging_missed
Ratio of slots missed by the Bridging Gadget Operator during an Epoch, calculated as missed slots divided by total slots.
R_bridging_missed_max
Maximum allowed ratio of missed slots before Bridging Gadget Operator is penalized and disabled in the next epoch.
Relay Chain
Polkadot's central blockchain that coordinates the network, provides shared security, and enables communication between parachains.
Remote Procedure Call (RPC)
A software communication protocol that enables a program to facilitate the execution of a specific procedure on a different blockchain network.
RocksDB
High-performance embedded database for key-value storage
RPC Layer
The communication protocol layer that enables applications to interact with the blockchain through standardized methods.
Runtime
The core logic of a blockchain that defines its state transition function.
S_batch_size
Number of Fast Chain blocks included in a single FCFP before submission to Bridging Gadget.
S_checkpoint_interval
Number of blocks between state checkpoints for fast synchronization
S_election_finalization
Number of blocks before epoch end when validator election results must be finalized.
S_epoch_duration
Duration between validator set elections, encompassing the full governance and nomination cycle.
S_fc_block_time
Target time between blocks during normal operation on Fast Chain, currently set to 100ms.
S_last_voting_block
Number of blocks before epoch end after which no more nominator votes are accepted.
S_secondary_delay
Number of consecutive slots the Primary Leader may miss before the Secondary Leader starts block production.
S_tenure_duration
Duration for which a single Primary Leader produces blocks before rotation to the next validator.
S_witness_delay
Time allocated for validators to submit witness messages during Finality Recovery Mode.
S_yell_response_delay
Number of slots validators wait for the Primary Leader to include Yell Query transaction and provide inclusion proof.
S_yell_user_delay
Number of slots user waits before submitting Yell Query, noted as unused due to mempool visibility subjectivity.
Secondary Leader
Backup block producer that activates when Primary Leader fails, maintaining chain liveness during recovery procedures.
Self-Consistency
A node's chain does not contradict its own previous chain at any later point.
Short-term Parallel Incremental Network agreement (SPIN)
Simple Concatenated Aggregate Little-Endian encoding (SCALE)
Simple Concatenated Aggregate Little-Endian encoding, used for efficient blockchain data serialization.
Slow Path (Fallback)
A fallback mechanism that activates if the accelerator misbehaves or is unresponsive. Reverts to a slower, standard blockchain consensus process.
SmartContract
Self-executing contract with terms directly written into code, running on a blockchain.
Smoldot
Lightweight blockchain client implementation that can run in browsers and resource-constrained environments
sp-trie
Polkadot SDK (ex Substrate)'s implementation of Patricia Merkle Tree for state storage
Squid SDK
Blockchain indexing framework for building APIs and explorers
State
Current snapshot of the network at a particular point in time, including information about accounts, balances, and other relevant data.
State Machine Replication (SMR)
A distributed systems abstraction where nodes agree on an ever-growing ordered log of commands.
State Root
Hash of the entire blockchain state, stored in block headers.
Storage
General term for how data is saved, managed, and accessed within the network.
Telemetry
Tenure
Fixed time period during which a single Primary Leader produces blocks before rotation to next validator.
TestNet
A more mature test network that replicates MainNet conditions, used for final testing before production deployment.
Transaction (TX)
A record of a transfer of value from one account to another, stored in a block and validated by the network.
Turing-complete
A system or language capable of performing any computation that a Turing machine can.
Validator node
A network participant responsible for validating and proposing new blocks based on staked assets and delegated stakes.
Verifiable Offchain Workers
System that handles complex computations outside the blockchain with cryptographic proof of correct execution.
View Change
A process triggered when participants detect that the current accelerator is malicious, slow, or unavailable. Elects a new accelerator.
Wallet
Software that stores private keys, displays account balances, and enables transaction signing.
WebRTC
Web Real-Time Communication, a collection of protocols and APIs for direct browser-to-browser communication.
Witness Message
Message submitted by validators during Finality Recovery Mode containing the latest finalized block hash produced by Primary Leader.
Write-Ahead Logging (WAL)
A technique that ensures data integrity by recording changes to a log before applying them to the ledger.
XCM
Cross-Consensus Message Format for communication between different consensus systems.
Yell Query
Anti-censorship mechanism allowing users to submit transactions to Bridging Gadget when they suspect Fast Chain censorship.
Yell Target Transaction (YTT)
Specific transaction that user believes is being censored by Primary Leader, referenced in Yell Query.
zkTLS
Zero-knowledge Transport Layer Security, a mechanism to securely attest Web2 data on-chain.
