Glossary

A glossary of essential terms, definitions, and concepts related to Avail.

App-Chain

An appchain is an independent blockchain tailored to a specific application's needs, providing dedicated performance and scalability without the constraints of a shared chain. Avail enables modular appchain architectures based on different layer 2 or 3 scaling solutions.

AVAIL

AVAIL is the native token of the Avail network. The AVAIL token is live on Mainnet; learn more about the AVAIL token here.

Avail JS Apps

The Avail JS Apps UI is a forked version of Polkadot JS Apps UI used for visualizing and interacting with the Avail network.

BABE

BABE (Blind Assignment for Blockchain Extension), part of the Substrate framework, is the block production mechanism that Avail uses. Refer to the Polkadot Wiki for more details.

Bonding

Bonding is the process of locking tokens to participate in network operations such as consensus and security.

Chilling

Chilling is the act of withdrawing from nominating or validating roles, effective in the subsequent era. It can also refer to a validator being excluded from the active set by peers, making them ineligible for the next consensus cycle.

Commission

Validators set a commission rate that is deducted from their block production rewards. The remaining rewards are distributed to nominators backing that validator.

Consensus

Consensus is the mechanism by which nodes agree on what blockchain data is valid. Avail uses NPoS as its consensus protocol.

Controller Account

The controller account manages staking activities — nominating validators, bonding/unbonding funds, and paying transaction fees. It is used more frequently than the stash account for day-to-day operations.

Data Attestation

Data attestation confirms the authenticity and accessibility of on-chain data. Avail block headers include KZG polynomial commitments for data and a Merkle tree root with data blobs as leaves. A supermajority of validators finalize headers using the GRANDPA protocol.

Data Availability Committee (DAC)

A DAC is a group of nodes that preserves copies of off-chain data and ensures its accessibility on demand. Unlike DACs, which typically serve specific L2 solutions, Avail is a general-purpose data availability layer that operates as an autonomous chain.

Data Availability Sampling (DAS)

DAS allows light clients to confirm data availability without downloading full blocks. Light clients randomly sample small chunks of block data across multiple rounds, with confidence growing after each successful round until a set threshold is reached.

DHT (Distributed Hash Table)

A DHT is a decentralized lookup system that holds key-value pairs, enabling peers to quickly find data. In Avail, the DHT facilitates sharing data cells for random sampling and proof verification, connecting nodes for efficient cell discovery and access.

Decoupling

Decoupling in blockchain refers to separating distinct functionalities into independent modules or layers. This modular approach allows each component to specialize, evolve, and scale independently.

Equivocation

Equivocation is when a validator signs two or more conflicting blocks or messages. This can be done intentionally or unintentionally.

Era

An era in Avail is a predefined number of sessions during which the validator set is determined and rewards are distributed. At each era boundary, validators are selected for the active set based on stake amount and prior performance.

Epoch

An epoch is a designated time frame during which a specific group of validators verifies transactions and appends them to the blockchain. Epoch duration varies across networks.

Execution

In traditional blockchains, execution is how nodes process transactions to transition state. Avail does not have a general-purpose execution layer — execution occurs in other layers (such as rollups), and the resulting data is posted to Avail in raw form. Avail validators do not execute transactions to attest to block validity. They primarily attest to the correct packaging of published data, which is why Avail can accommodate larger block sizes with reduced per-block overhead.

Finality Gadget

A finality gadget ensures blockchain state finality by requiring validators to commit through signed messages. Once sufficiently validated, the state is finalized and secure from modification.

Fraud Proofs

Fraud proofs are cryptographic proofs used to challenge the legitimacy of a transaction or state transition. Any node can generate and share a fraud proof across the P2P network for app clients to assess.

GRANDPA

GRANDPA (GHOST-based Recursive Ancestor Deriving Prefix Agreement), part of the Substrate framework, is the finality gadget Avail uses. Refer to the GRANDPA paper for the full protocol description.

KZG Commitments

KZG commitments, introduced by Kate, Zaverucha, and Goldberg in 2010, are a concise method for committing to polynomials. Avail uses KZG commitments because they enable succinct commitments for block headers, support brief openings for light client verification, and provide strong cryptographic binding that prevents fraudulent commitments.

Kademlia DHT (Kad-DHT)

Kad-DHT is a DHT variant that organizes nodes on a chord ring ordered by ID. Avail uses Kad-DHT to store data cells and locate which peer holds a particular data segment, with matrix data cells uniquely mapped to Peer IDs.

libp2p

libp2p is an open-source modular network stack for building P2P applications. Avail integrates libp2p to establish a decentralized network for data availability, ensuring transaction data is efficiently stored and disseminated to validators and full nodes.

Light Client

Light clients allow users to interact with a blockchain without syncing the full chain, typically retrieving only block headers. Avail light clients enhance this with Data Availability Sampling, downloading and verifying random block segments to confirm content availability.

Mainnet

A mainnet is the fully operational, public "production" version of a blockchain network where real transactions and applications run. See the "Mainnet is Live!" blog post for details on Avail's mainnet.

Modular Blockchain

A modular blockchain specializes in specific tasks while delegating other responsibilities to distinct layers or components.

Monolithic Blockchain

A monolithic blockchain handles all core functionalities (execution, settlement, ordering, data availability) within a single structure.

Nominated Proof of Stake

Nominated Proof of Stake (NPoS) is a consensus algorithm where users nominate validators to produce blocks on their behalf. Validators receive rewards in native tokens and share a portion with nominators based on a set commission rate. Avail uses NPoS as implemented within Substrate.

Oversubscribed

Oversubscribed refers to when the number of nominators wishing to participate exceeds the available slots.

Scalability

Scalability in Avail refers to increasing the volume of data the chain can disseminate without degrading participant experience. Avail achieves this through a modular approach that moves DA off-chain, allowing each component to scale independently.

Session

A session is a specific duration during which a fixed set of validators operate. Validators can enter or exit the set only at session boundaries.

Settlement

Settlement is the process by which modular layers agree on the correct execution outcome of transaction data. Avail receives and stores raw transaction data without executing it — actual execution and validation occur in other layers, with results settled through mechanisms like validity proofs on Ethereum.

Slashing

Slashing is a penalty imposed on validators who misbehave (e.g., equivocation). It can result in the loss of a portion of the validator's stake.

Sovereign Rollup

A sovereign rollup publishes transactions to another blockchain for ordering and data availability but handles its own settlement. It maintains its own canonical chain and validity rules without relying on an external settlement layer.

Stash Account

The stash account holds the tokens you wish to stake/bond. It functions as cold storage and is used for bonding, unbonding, and designating the controller account.

Testnet

A testnet is a simulated blockchain network used to test and debug applications before mainnet deployment. Testnets are typically open to public participation.

Validium

A validium stores transaction data off the primary L1 (e.g., Ethereum) and can leverage Avail's scalable DA module. Rather than directing data to a DAC or other alternatives, validiums can commit data to Avail. Essentially, a validium is a rollup with off-chain data availability.

Validator

An Avail validator is a full node responsible for verifying transactions and adding them to the blockchain.

Volition

A volition is an advanced form of zero-knowledge rollup that lets developers choose whether to store transaction data on-chain or off-chain. Volitions can leverage Avail's DA layer to keep off-chain data accessible and verifiable, optimizing for both cost and availability.

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Glossary

A glossary of essential terms, definitions, and concepts related to Avail.

App-Chain

AVAIL

AVAIL is the native token of the Avail network. The AVAIL token is live on Mainnet; learn more about the AVAIL token here.

Avail JS Apps

The Avail JS Apps UI is a forked version of Polkadot JS Apps UI used for visualizing and interacting with the Avail network.

BABE

BABE (Blind Assignment for Blockchain Extension), part of the Substrate framework, is the block production mechanism that Avail uses. Refer to the Polkadot Wiki for more details.

Bonding

Bonding is the process of locking tokens to participate in network operations such as consensus and security.

Chilling

Commission

Validators set a commission rate that is deducted from their block production rewards. The remaining rewards are distributed to nominators backing that validator.

Consensus

Consensus is the mechanism by which nodes agree on what blockchain data is valid. Avail uses NPoS as its consensus protocol.

Controller Account

Data Attestation

Data Availability Committee (DAC)

Data Availability Sampling (DAS)

DHT (Distributed Hash Table)

Decoupling

Decoupling in blockchain refers to separating distinct functionalities into independent modules or layers. This modular approach allows each component to specialize, evolve, and scale independently.

Equivocation

Equivocation is when a validator signs two or more conflicting blocks or messages. This can be done intentionally or unintentionally.

Era

Epoch

An epoch is a designated time frame during which a specific group of validators verifies transactions and appends them to the blockchain. Epoch duration varies across networks.

Execution

Finality Gadget

A finality gadget ensures blockchain state finality by requiring validators to commit through signed messages. Once sufficiently validated, the state is finalized and secure from modification.

Fraud Proofs

GRANDPA

GRANDPA (GHOST-based Recursive Ancestor Deriving Prefix Agreement), part of the Substrate framework, is the finality gadget Avail uses. Refer to the GRANDPA paper for the full protocol description.

KZG Commitments

Kademlia DHT (Kad-DHT)

libp2p

Light Client

Mainnet

Modular Blockchain

A modular blockchain specializes in specific tasks while delegating other responsibilities to distinct layers or components.

Monolithic Blockchain

A monolithic blockchain handles all core functionalities (execution, settlement, ordering, data availability) within a single structure.

Nominated Proof of Stake

Oversubscribed

Oversubscribed refers to when the number of nominators wishing to participate exceeds the available slots.

Scalability

Session

A session is a specific duration during which a fixed set of validators operate. Validators can enter or exit the set only at session boundaries.

Settlement

Slashing

Slashing is a penalty imposed on validators who misbehave (e.g., equivocation). It can result in the loss of a portion of the validator's stake.

Sovereign Rollup

Stash Account

The stash account holds the tokens you wish to stake/bond. It functions as cold storage and is used for bonding, unbonding, and designating the controller account.

Testnet

A testnet is a simulated blockchain network used to test and debug applications before mainnet deployment. Testnets are typically open to public participation.

Validium

Validator

An Avail validator is a full node responsible for verifying transactions and adding them to the blockchain.

Volition

How is this guide?

Get Submission Information

FAQs

Search Documentation

Glossary

App-Chain

AVAIL

Avail JS Apps

BABE

Bonding

Chilling

Commission

Consensus

Controller Account

Data Attestation

Data Availability Committee (DAC)

Data Availability Sampling (DAS)

DHT (Distributed Hash Table)

Decoupling

Equivocation

Era

Epoch

Execution

Finality Gadget

Fraud Proofs

GRANDPA

KZG Commitments

Kademlia DHT (Kad-DHT)

libp2p

Light Client

Mainnet

Modular Blockchain

Monolithic Blockchain

Nominated Proof of Stake

Oversubscribed

Scalability

Session

Settlement

Slashing

Sovereign Rollup

Stash Account

Testnet

Validium

Validator

Volition

Search Documentation

Glossary

App-Chain

AVAIL

Avail JS Apps

BABE

Bonding

Chilling

Commission

Consensus

Controller Account

Data Attestation

Data Availability Committee (DAC)

Data Availability Sampling (DAS)

DHT (Distributed Hash Table)

Decoupling

Equivocation

Era

Epoch

Execution

Finality Gadget

Fraud Proofs

GRANDPA

KZG Commitments

Kademlia DHT (Kad-DHT)

libp2p

Light Client

Mainnet

Modular Blockchain

Monolithic Blockchain

Nominated Proof of Stake

Oversubscribed

Scalability

Session

Settlement

Slashing

Sovereign Rollup

Stash Account