Accelerator
Consensus
A designated special player responsible for fast transaction confirmations during optimistic scenarios.
Comment: Similar to the Leader in SPIN consensus
Actively Used in Project
Terms (A–Z)
Section titled “Terms (A–Z)”A
Archive node
Node Types
A node that stores a complete record of states for every block and the entire blockchain history.
Comment: Final source of truth Used for verification the balance of a specific account for a specific time
Authority-based round-robin scheduling (AURA)
Consensus
Provides a slot-based block authoring mechanism, where a known set of authorities take turns producing blocks.
Comment: Used in some Polkadot SDK-based (ex Substrate) chains. One of the potential base consensus options for QF Network's SPIN implementation.
B
Blind Assignment for Blockchain Extension (BABE)
Consensus
Polkadot's block production mechanism
Comment: Used in some Polkadot SDK-based (ex Substrate) chains. One of the potential base consensus options for QF Network's SPIN implementation.
Blob
Storage
Binary data stored on the blockchain, particularly in smart contract context.
Comment: Used in PolkaVM for smart contract code storage, e.g. https://github.com/QuantumFusion-network/spec/blob/main/docs/PolkaVM/blob_hashing_addressing.md
Block
Core terms
A collection of data, such as transactions, that together indicate a state transition of the blockchain.
Comment: Typically contains: transaction data, hash, previous block hash, validator information
Block Explorer
User Interface
A web tool for inspecting and navigating detailed blockchain data, including blocks, transactions, addresses, and smart contracts.
Comment: Part of portal. Contains block viewer Examples: https://etherscan.io, https://subscan.io More focused than a portal but more comprehensive than a block viewer. Block explorers provide search functionality and detailed transaction data.
Block Viewer
User Interface
A simplified interface specifically for viewing basic block data and recent transactions without the additional analysis features of a full explorer.
Comment: Part of block explorer (part of portal) Examples: https://blockchair.com/bitcoin/blocks, https://www.blockchain.com/explorer/blocks/btc The simplest of the three interfaces. Block viewers show core blockchain activity with minimal complexity.
Blockchain
Core terms
A distributed ledger technology that maintains a continuously growing list of records (blocks) secured using cryptography.
Blockchain Trilemma
Core terms
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
Node Types
Initial node that helps others connect to the network.
Comment: Used during peer discovery.
Bulk Coretime
Core terms
A purchasing model for parachain slots on Polkadot using bulk time allocation.
C
Chain Growth
Chain Quality
Consensus
Minimum portion of blocks from honest nodes.
Comment: Ensures integrity under partial corruption.
Collator
Node Types
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).
Comment: Collects parachain transactions and produces state transition proofs (Proof-of-Validity, PoV) for the validators. In the context of SPIN, Fast Chain Validators also serve as Collators (specifically, as Bridging Gadget Operators) to carry out information relaying duties and submit information to the Anchor Chain
Committee
Consensus
A predefined subset of nodes tasked with verifying transactions rapidly in cooperation with the Leader
Comment: Works with Leader (Accelerator) for quick notarization.
Common Prefix
Consensus
A consistency property: the chain of an honest node is a prefix of any other honest node's chain.
Consensus
Core terms
The process by which network participants agree on the state of the blockchain
Comment: Ensures all nodes have a consistent view of the ledger, securing the system against fraud and discrepancies.
Consistency, Availability, and Partition Tolerance (CAP theorem)
Core terms
Theorem states that a distributed data store can only provide two out of the following three guarantees simultaneously: Consistency, Availability, and Partition Tolerance.
Coretime
D
Dashboard
User Interface
Visual overview of network performance, blocks, and usage.
Comment: Supports validators and telemetry
decentralized Application (dApp)
Development UI
Application that interacts with a blockchain using RPC to read data and a wallet to write to the blockchain.
Comment: Frontend integrates with smart contracts.
DevNet
Core terms
A development network environment for early testing of blockchain functionality before TestNet deployment.
Comment: Demonstrating core functionality with a small number of validator nodes.
E
EcoSystem
Core terms
The complete environment of interconnected applications, services, and components that make up the blockchain network.
Extrinsic
Development
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.
Comment: The mechanism for submitting operations
F
Fast Path
Consensus
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
Development UI
A service that distributes test tokens to users on DevNet or TestNet
Comment: Allows developers to obtain tokens for testing without purchasing or mining. Repo: https://github.com/QuantumFusion-network/devnet-faucet
Finalized Block
Core terms
A block that has been accepted as canonical and will not be reverted.
Comment: Used in finality (e.g. GRANDPA).
Forkless Runtime Upgrades
Architecture
A mechanism to update blockchain logic without requiring hard forks.
Comment: Inherited from Polkadot SDK (ex Substrate)
Framework for Runtime Aggregation of Modularized Entities (FRAME)
Full node
Node Types
A node that stores the entire blockchain history and current state, validates transactions and blocks.
Comment: Serves as the final source of truth in the network, executes transactions, and provides Merkle proofs to light nodes.
G
Gas
Transactions
A fee or cost required to conduct a transaction on the blockchain, denominated in small fractions of cryptocurrency
Comment: If the transaction fails, the gas will be debited, but the transaction will have to be restarted and the gas will have to be paid for again.
Gas limit
Transactions
The maximum price a cryptocurrency user is willing to pay when sending a transaction, or performing a smart contract function.
Gas Metering
Transactions
System for measuring and limiting computational resources used by transactions or smart contracts.
Genesis Block
Core terms
The first block of the blockchain from which all subsequent blocks build.
GHOST-based Recursive Ancestor Deriving Prefix Agreement (GRANDPA)
Consensus
A finality gadget for blockchain consensus.
Comment: A finality gadget used in blockchain consensus. In the SPIN protocol, it serves as one of the potential asynchronous finality methods for the Fast Chain and is used in the Relay Chain for finality validation
Gossip Protocol
Graceful Degradation
Consensus
Ensures system performance transitions smoothly from an optimal fast path to a slower consensus mechanism without failure.
H
History
Storage
Chronological sequence of confirmed blocks and finalized states.
Comment: Typicaly retained via Archive Nodes and used in sync and audit logic
I
Instant Confirmation
Consensus
The capability to confirm transactions almost immediately (within network delay bounds) under optimistic conditions.
K
Key Management
Development
Tools and practices for managing cryptographic keys.
L
Layer 1 (L1)
Core terms
The base layer of blockchain architecture that includes data storage, transaction processing, consensus, and RPC.
Comment: Parachain on Polkadot
Light Client
Node Types
A blockchain client that stores minimal data and relies on full nodes for verification.
Comment: Enables mobile support.
Light node
Node Types
A node that stores only part of the blockchain state and verifies data using full nodes.
Comment: Similar for Light Client. Included by default in user apps, can run transactions but has limited storage requirements.
Log-Structured Merge Tree (LSM tree)
Storage
Data structure that is optimized for write-heavy workloads.
Comment: Used in PolkaVM. Works by collecting writes in memory and periodically merging them into larger, on-disk structures.
M
MainNet
Core terms
The production blockchain network where real-value transactions occur.
Merkle Proof
Storage
Cryptographic verification mechanism that allows light nodes to verify data without storing the entire blockchain.
Comment: Enables light clients.
Merkle Tree
Storage
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.
Comment: Used for efficient and secure verification of large data structures.
Metadata
Core terms
Data that includes information about other data, such as information about a specific transaction.
Metric(s)
Development
Quantifiable measurements used to track and assess the status of specific processes in the blockchain.
Comment: Includes block time, TPS, forks, etc.
N
Node (as blockchain node)
Node Types
A machine running the blockchain engine, which can store blocks and participate in the network.
Comment: Has properties related to data storage, transaction capabilities, consensus participation, and RPC provision.
Node (as network node)
Core terms
A node that participates in network exchange, for example, a seed server
Nominated Proof of Stake (NPoS)
Consensus
A consensus mechanism where network participants (nominators) delegate their stake to trusted validator nodes.
Comment: Validators are selected based on both their own stake and the stakes they receive from nominators. QF Network, which is built using the SPIN consensus, uses a derivative of Phragmen for NPoS to elect and prove its Validator Set selection
O
Optimistic Conditions
Consensus
Conditions where the leader is honest and available, and a large fraction of nodes are correct, enabling fast-path confirmation.
Optimistic Responsiveness
Consensus
Confirms transactions as fast as the actual message delay in the network, assuming a supermajority of honest players and an honest accelerator.
Orphaned Block
Core terms
A block that has not reached finalization.
Comment: Transactions from orphaned blocks are typically taken and included in new blocks for finalization.
P
Pallet
Development
Modular component in Polkadot SDK (ex Substrate) that implements specific blockchain functionality.
Comment: Used for functionality like balances, assets, and consensus.
Parachain
Core terms
A specialized blockchain that runs in parallel to Polkadot's Relay Chain, sharing its security and interoperability features
Comment: QF Network operates as a parachain on Polkadot, inheriting its security model while maintaining sovereignty
Pessimistic Conditions
Consensus
Conditions under which optimistic assumptions fail, causing the protocol to fall back to slower consensus.
Comment: Triggers recovery mode.
Portal
User Interface
A comprehensive web interface for interacting with a blockchain network that combines multiple tools including block exploration, wallet connectivity, network statistics, and developer tools.
Comment: A portal is the broadest interface type, providing a complete ecosystem entry point. A portal typicaly includes block explorer functionality, wallet connections, network monitoring, and developer tools in one unified interface.
Precompile
Development
Built-in functions in blockchain runtime that execute at near-native speed.
Comment: Used for frequently needed operations like cryptographic functions.
ProofStorage
Storage
A mechanism for generating Merkle proofs from blockchain state.
Comment: Enables light client sync.
Pruning Node
Node Types
A node that discards older blocks to save storage space while maintaining current state.
Comment: Will be implemented in a future phase when accelerated sync through checkpoints becomes available.
R
Relay Chain
Core terms
Polkadot's central blockchain that coordinates the network, provides shared security, and enables communication between parachains.
Comment: Provides security and finality services to QF Network as a parachain. In SPIN context, serves as the Anchor Chain.
Remote Procedure Call (RPC)
Core terms
A software communication protocol that enables a program to facilitate the execution of a specific procedure on a different blockchain network.
Comment: Examples of RPC frameworks or formats: - JSON-RPC (JavaScript Object Notation Remote Procedure Call) - gRPC - Cap'n Proto
RPC Layer
Infrastructure
The communication protocol layer that enables applications to interact with the blockchain through standardized methods.
Runtime
Core terms
The core logic of a blockchain that defines its state transition function.
Comment: It defines a valid algorithm for determining the state of the next block given the previous state. Can be upgraded through forkless upgrades. Defined by FRAME modules.
S
Self-Consistency
Consensus
A node's chain does not contradict its own previous chain at any later point.
Comment: Used for validator safety.
Short-term Parallel Incremental Network agreement (SPIN)
Simple Concatenated Aggregate Little-Endian encoding (SCALE)
Infrastructure
Simple Concatenated Aggregate Little-Endian encoding, used for efficient blockchain data serialization.
Slow Path (Fallback)
Consensus
A fallback mechanism that activates if the accelerator misbehaves or is unresponsive. Reverts to a slower, standard blockchain consensus process.
Comment: Triggers view change.
SmartContract
Development
Self-executing contract with terms directly written into code, running on a blockchain.
State
Storage
Current snapshot of the network at a particular point in time, including information about accounts, balances, and other relevant data.
Comment: Each state has a hash (Merkle Proof). Includes transaction storage and global state of all blockchain.
State Machine Replication (SMR)
Consensus
A distributed systems abstraction where nodes agree on an ever-growing ordered log of commands.
State Root
Core terms
Hash of the entire blockchain state, stored in block headers.
Comment: Enables efficient proof verification.
Storage
Uncategorized
General term for how data is saved, managed, and accessed within the network.
T
Telemetry
TestNet
Core terms
A more mature test network that replicates MainNet conditions, used for final testing before production deployment.
Comment: Mirrors production logic.
Transaction (TX)
Transactions
A record of a transfer of value from one account to another, stored in a block and validated by the network.
Comment: Transactions for execution are ranked based on gas price/CPU cycle Custom transactions in Polkadot SDK (ex Substrate) – a democratic discussion on proposing a new runtime
Turing-complete
Core terms
A system or language capable of performing any computation that a Turing machine can.
Comment: In the context of SPIN, the Turing-completeness of the Anchor Chain is a vital property. This allows for the execution of complex smart contracts, which is essential for implementing the Bridging Gadget and enabling advanced recovery procedures. SPIN drafts also noted the "Turing-complete flexibility of our Anchor chain" as a factor in handling errors
V
Validator node
Node Types
A network participant responsible for validating and proposing new blocks based on staked assets and delegated stakes.
Comment: Participates in consensus to propose and finalize blocks. Can use goodwill - a return mechanism if the sender makes a mistake and confuses gas values with money for a transfer
Verifiable Offchain Workers
Architecture
System that handles complex computations outside the blockchain with cryptographic proof of correct execution.
Comment: Enables support compute-intensive operations while maintaining fast block times.
View Change
Consensus
A process triggered when participants detect that the current accelerator is malicious, slow, or unavailable. Elects a new accelerator.
Comment: Similar to leader rotation in SPIN consensus.
W
Wallet
User Interface
Software that stores private keys, displays account balances, and enables transaction signing.
Comment: Stores cryptographic keys, queries node for account information, and generates transaction signatures.
Write-Ahead Logging (WAL)
Storage
A technique that ensures data integrity by recording changes to a log before applying them to the ledger.
Comment: Allows the system to recover to a consistent state in case of failures.
X
XCM
Infrastructure
Cross-Consensus Message Format for communication between different consensus systems.
Comment: Used for integration with the Polkadot ecosystem.
Z
zkTLS
Security
Zero-knowledge Transport Layer Security, a mechanism to securely attest Web2 data on-chain.
Comment: Used to bring Web2 data onto the blockchain in a verifiable way.